Sample records for cretaceous sandstone hydrocarbon

  1. Reservoir attributes of a hydrocarbon-prone sandstone complex: case of the Pab Formation (Late Cretaceous) of Southwest Pakistan

    DEFF Research Database (Denmark)

    Umar, Muhammad; Khan, Abdul Salam; Kelling, Gilbert;


    Links between the architectural elements of major sand bodies and reservoir attributes have been explored in a field study of the hydrocarbon-yielding Late Cretaceous Pab Formation of southwest Pakistan. The lithofacies and facies associations represented in the Pab Formation are the main...... porosity values than more shale-rich successions. Diagenetic studies of Pab sandstones reveal that intense mechanical compaction and cementation have reduced primary porosity and reservoir quality. Conversely, dissolution of detrital feldspar grains and volcanic fragments during burial and later uplift...

  2. Upper Jurassic - Lower Cretaceous turbidite sandstones in the Central Graben, North Sea; with special focus on the Danish Gertrud Graben

    Energy Technology Data Exchange (ETDEWEB)

    Johannessen, P.


    Thick Late Jurassic - Early cretaceous turbidite sandstone successions in the Central Graben are uncommon except from the Moray Firth and Viking Graven north of the Central Graben, where several important hydrocarbon producing turbidite sandstone fields are known. The only hydrocarbon producing turbidite reservoir sandstones in the Central Graben is the up to 55 m thick Ribble Sandstone Member located in the British South-west Central Graben, where it is lying above thick shoreface reservoir sandstones of the Fulmar Formation, separated by offshore claystones of the Kimmeridge Clay Formation. The turbidite sandstones of the Ribble Sandstone Member derived from the more proximal thick reservoir sandstones of the Fulmar Formation located near the Mid North Sea High. It has not yet been possible to correlate thick shoreface sandstones of the Norwegian Ula Formation or the Danish Heno Formation to more distal thick turbidite sandstones derived from the shoreface sandstones. (au) 60 fig., 85 refs.

  3. Diagenesis and reservoir quality of the Lower Cretaceous Quantou Formation tight sandstones in the southern Songliao Basin, China (United States)

    Xi, Kelai; Cao, Yingchang; Jahren, Jens; Zhu, Rukai; Bjørlykke, Knut; Haile, Beyene Girma; Zheng, Lijing; Hellevang, Helge


    The Lower Cretaceous Quantou Formation in the southern Songliao Basin is the typical tight oil sandstone in China. For effective exploration, appraisal and production from such a tight oil sandstone, the diagenesis and reservoir quality must be thoroughly studied first. The tight oil sandstone has been examined by a variety of methods, including core and thin section observation, XRD, SEM, CL, fluorescence, electron probing analysis, fluid inclusion and isotope testing and quantitative determination of reservoir properties. The sandstones are mostly lithic arkoses and feldspathic litharenites with fine to medium grain size and moderate to good sorting. The sandstones are dominated by feldspar, quartz, and volcanic rock fragments showing various stages of disintegration. The reservoir properties are quite poor, with low porosity (average 8.54%) and permeability (average 0.493 mD), small pore-throat radius (average 0.206 μm) and high displacement pressure (mostly higher than 1 MPa). The tight sandstone reservoirs have undergone significant diagenetic alterations such as compaction, feldspar dissolution, quartz cementation, carbonate cementation (mainly ferrocalcite and ankerite) and clay mineral alteration. As to the onset time, the oil emplacement was prior to the carbonate cementation but posterior to the quartz cementation and feldspar dissolution. The smectite to illite reaction and pressure solution at stylolites provide a most important silica sources for quartz cementation. Carbonate cements increase towards interbedded mudstones. Mechanical compaction has played a more important role than cementation in destroying the reservoir quality of the K1q4 sandstone reservoirs. Mixed-layer illite/smectite and illite reduced the porosity and permeability significantly, while chlorite preserved the porosity and permeability since it tends to be oil wet so that later carbonate cementation can be inhibited to some extent. It is likely that the oil emplacement occurred

  4. Hydrocarbon migration characteristics of the Lower Cretaceous in the Erlian Basin

    Institute of Scientific and Technical Information of China (English)


    The paper systematically analyzes the hydrocarbon migration characteristics of the Lower Cretaceous in the Erlian Basin, based on the geochemical data of mudstone and sandstone in the main hydrocarbon-generating sags. (1) The source rocks in K1ba and K1bt1 are estimated to be the mature ones, their hydrocarbon expulsion ratio can reach 32%-72%. The Type-I sags in oil windows possess good hydrocarbon generation and expulsion conditions, where commercial reservoirs can be formed. (2) According to the curves of the mudstone compaction and evolution of clay minerals, the rapid compaction stage of mudstones is the right time of hydrocarbon expulsion, i.e., primary migration. (3) The timing between hydrocarbon generation and expulsion is mainly related to the accordance of the oil window and the rapid compaction stage of mudstones in the hydrocarbon generation sags of Type-I. That forms the most matching relation between hydrocarbon generation and migration. (4) The faults and unconformities are the important paths for the secondary hydrocarbon migration. Especially, the unconformity between K1ba and K1bt1 has a favorable condition for oil accumulation, where the traps of all types are the main exploration targets. (5) Hydrocarbon migration effect, in the Uliastai sag, is most significant; that in the Saihan Tal and Anan sags comes next, and that in the Bayandanan and Jargalangt sags is worst.

  5. Hydrocarbon accumulation model of the Cretaceous in southern China

    Institute of Scientific and Technical Information of China (English)


    The Cretaceous in southern China is mainly a set of red and mauve clastic rock,with evaporation layers. For lack of source rock,it has been paid little attention to in the exploration process. With the development of research on hydrocarbon exploration,the masses of Cretaceous reservoirs and shows have been found in recent years. This means that the Cretaceous has great exploration potential. According to the research,authors find that the high-quality reservoir and efficient cap rocks develop in the Cretaceous. At the same time,the Cretaceous and underlying Paleozoic-Early Mesozoic marine strata and overlying Cenozoic nonmarine strata constitute a superimposed basin. Moreover,high-quality source rocks developed in the above-mentioned two sets of strata. In the south,especially in the middle and lower Yangtze region since the Himalayan strong rift was associated with a large number of faults,These faults connect the Cretaceous reservoir and its overlying and underlying source rocks,forming the fault-based and unconformity-based discontinuous source-reservoir-cap accumulation assemblages. Because the Cretaceous has the abundant oil and gas from Paleogene source rocks or Mesozoic–Paleozoic source rocks with secondary hydrocarbon generation ability,three types of reservoirs develop in the Cretaceous:"new-generating and old-reservoiring" reservoirs,"old-generating andnew-reservoiring" reservoirs,and few "self-generating andself-reservoiring" reservoirs. The hydrocarbon enrichment depends on two key factors. Firstly,Cretaceous reservoirs are near to the source kitchens,so its oil and gas source is ample. Secondly,the fault system is well developed,which provides the necessary conducting systems for hydrocarbon accumulation.

  6. Petroleum system and production characteristics of the Muddy (J) Sandstone (Lower Cretaceous) Wattenberg continuous gas field, Denver basin, Colorado (United States)

    Higley, D.K.; Cox, D.O.; Weimer, R.J.


    Wattenberg field is a continuous-type gas accumulation. Estimated ultimate recovery from current wells is 1.27 tcf of gas from the Lower Cretaceous Muddy (J) Sandstone. Mean gas resources that have the potential to be added to these reserves in the next 30 yr are 1.09 tcf; this will be primarily through infill drilling to recover a greater percentage of gas in place and to drain areas that are isolated because of geologic compartmentalization. Greatest gas production from the Muddy (J) Sandstone in Wattenberg field occurs (1) from within the most permeable and thickest intervals of Fort Collins Member delta-front and nearshore-marine sandstones, (2) to a lesser extent from the Horsetooth Member valley-fill channel sandstones, (3) in association with a large thermal anomaly that is delineated by measured temperatures in wells and by vitrinite reflectance contours of 0.9% and greater, (4) in proximity to the bounding Mowry, Graneros, and Skull Creek shales that are the hydrocarbon source rocks and reservoir seals, and (5) between the Lafayette and Longmont right-lateral wrench fault zones (WFZs) with secondary faults that act as conduits in areas of the field. The axis of greatest gas production is north 25 to 35?? northeast, which parallels the basin axis. Recurrent movement along five right-lateral WFZs that crosscut Wattenberg field shifted the Denver basin axis to the northeast and influenced depositional and erosional patterns of the reservoir and seal intervals. Levels of thermal maturity within the Wattenberg field are anomalously high compared to other areas of the Denver basin. The Wattenberg field thermal anomaly may be due to upward movement of fluids along faults associated with probable igneous intrusions. Areas of anomalous high heat flow within the field correlate with an increased and variable gas-oil ratio.

  7. On the water saturation calculation in hydrocarbon sandstone reservoirs

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    Stalheim, Stein Ottar


    The main goal of this work was to identify the most important uncertainty sources in water saturation calculation and examine the possibility for developing new S{sub w} - equations or possibility to develop methods to remove weaknesses and uncertainties in existing S{sub w} - equations. Due to the need for industrial applicability of the equations we aimed for results with the following properties: The accuracy in S{sub w} should increase compared with existing S{sub w} - equations. The equations should be simple to use in petrophysical evaluations. The equations should be based on conventional logs and use as few as possible input parameters. The equations should be numerical stable. This thesis includes an uncertainty and sensitivity analysis of the most common S{sub w} equations. The results are addressed in chapter 3 and were intended to find the most important uncertainty sources in water saturation calculation. To increase the knowledge of the relationship between R{sub t} and S{sub w} in hydrocarbon sandstone reservoirs and to understand how the pore geometry affects the conductivity (n and m) of the rock a theoretical study was done. It was also an aim to examine the possibility for developing new S{sub w} - equations (or investigation an effective medium model) valid inhydrocarbon sandstone reservoirs. The results are presented in paper 1. A new equation for water saturation calculation in clean sandstone oil reservoirs is addressed in paper 2. A recommendation for best practice of water saturation calculation in non water wet formation is addressed in paper 3. Finally a new equation for water saturation calculation in thinly interbedded sandstone/mudstone reservoirs is presented in paper 4. The papers are titled: 1) Is the saturation exponent n a constant. 2) A New Model for Calculating Water Saturation In 3) Influence of wettability on water saturation modeling. 4) Water Saturation Calculations in Thinly Interbedded Sandstone/mudstone Reservoirs. A

  8. Upper cretaceous to paleocene depositional sequences and sandstone petrography of southwestern Patagonia (Argentina and Chile) (United States)

    Macellari, C. E.; Barrio, C. A.; Manassero, M. J.

    Upper Cretaceous to Paleocene strata exposed along the Andean margin of Patagonia south of 50°S were deposited in a foreland basin and comprise a complex transition from continental to marine facies. Three unconformity-bounded sequences are observed within the sedimentary succession studied. Sequence 1 (upper Campanian) displays a rapid north-to-south transition from upper delta plain mudstones (Cerro Fortaleza Formation) through lower delta plain and subaqueous delta plain sandstones (La Anita Formation) to delta-slope and basinal turbidites (Alta Vista and Tres Pasos Formations). Sequence 2 (Maastrichtian-Paleocene) was initiated with braided river sediments (La Irene Formation), deposited over a Type II unconformity ( sensu Vail et al., 1984). These rocks are overlain by meandering fluvial sandstones and mudstones (Chorrillo Formation) that interfinger to the south with fossiliferous shallow marine sandstones (upper Cerro Cazador Formation). Sequence 3 (Paleocene) is composed of shallow marine conglomerates and crossbedded sandstones (Calafate and Cerro Dorotea Formations). These rocks are separated by an angular unconformity from subjacent units. Sandstone petrographic analysis indicates the presence of two main petrofacies within the rocks studied. A quartz-rich petrofacies, present to the north of the basin during late Campanian to early Maastrichtian time, was derived from continental crustal block and recycled orogen sources that were possibly exposed to the northwest of the basin. The second petrofacies (volcanic-rich petrofacies) was restricted to the south of the basin during the late Campanian to early Maastrichtian, but covered the entire area during the late Maastrichtian and Paleocene. These sediments were derived from a dissected magmatic arc located to the west of the study area. The presence of abundant tuffaceous intercalations, as well as fresh andesitic fragments, indicates contemporaneous volcanism near the Cretaceous/Tertiary boundary. The

  9. Trap architecture of the Early Cretaceous Sarir Sandstone in the eastern Sirt Basin, Libya

    Energy Technology Data Exchange (ETDEWEB)

    Gras, R. [Schlumberger GeoQuest, Cedex (France); Thusu, B. [Arabian Gulf Oil Company, Benghazi (Libyan Arab Jamahiriya)


    The Sarir Sandstone is the principal reservoir for oil accumulations in the eastern Sirt Basin in Libya. The main phase of the rifting in this area took place in the Late Jurassic-Early Cretaceous, during which time the Sarir Sandstone was deposited as a non-marine, intra-continental clastic syn-rift sequence. Although successfully explored from 1959 onwards, the prolific eastern Sirt Basin is in a relatively immature stage of exploration regarding wildcat drilling and 3D seismic data acquisition. The most recent phase of exploration, utilizing 3D seismic techniques, revealed a complex structural development. The trap geometries are often related to E-W trending, basement-controlled fault systems, oblique to the NNW-SSE Sirt Basin trend. The fault systems were active during the Sarir Sandstone deposition, giving rise to structural as well as combined structural-traps. An increased understanding of trap architecture has led to both re-evaluation of older fields and new discoveries. (author)

  10. Sequence stratigraphy of the marine and non-marine Upper Cretaceous Dakota Sandstone, San Juan Basin, USA

    Energy Technology Data Exchange (ETDEWEB)

    Johannessen, P.


    Late Cretaceous, middle Cenomanian, shallow marine and non-marine sandstones of the Dakota Sandstone have been studied in the western part of the Western Interior, San Juan Basin, New Mexico. 15-20 m thick sharp based, slightly coarsening upward shoreface sandstones characterize the eastern fully marine part of the San Juan Basin, while non-marine sediments dominate the western part of the basin. The aim of this paper is to carefully correlate key-surfaces from the thick shoreface sandstones towards the west into the non-marine succession, using sequence stratigraphic principles. The present paper will document an additional marine sandstone underlying the Cubero Tongue; the Oak Canyon Member. (au)

  11. Discussion on origin of clay minerals in outcropped sandstone from Lower Cretaceous Chengzihe Formation and Muling Formation in Jixi Basin

    Institute of Scientific and Technical Information of China (English)

    LIU Jianying; LIU Li; QU Xiyu


    Clay minerals in the outcropped sandstone from Lower Cretaceous Chengzihe Formation and Muling Formation in Jixi Basin were analyzed by X-ray diffraction. The results show that the clay minerals mainly consist of illite, kaollinite and illite/smectite, which can be divided into two types: kaolinite- and illite/smectite types. The outcropped sandstone occurred in middle diagenetic stage-A on the basis of the clay mineral composition. The development factor of the formation of kaolinite type clay mineral is caused mainly by the organic acid from the coal-bearing formation and mudstone during the diagenesis process in Lower Cretaceous Chengzihe Formation and Muling Formation in the Jixi Basin. The weak hydrodynamic force of sedimentary facies made the sandstone leaching condition poor, which is the reason forming the aggregation of clay minerals of the illite/smectite-and illite types.

  12. Submarine-fan facies associations of the Upper Cretaceous and Paleocene Gottero Sandstone, Ligurian Apennines, Italy (United States)

    Nilsen, Tor H.; Abbate, Ernesto


    The Upper Cretaceous and Paleocene Gottero Sandstone was deposited as a small deep-sea fan on ophiolitic crust in a trench-slope basin. It was thrust northeastward as an allochthonous sheet in Early and Middle Cenozoic time. The Gottero, as thick as 1500 m, was probably derived from erosion of Hercynian granites and associated metamorphic rocks in northern Corsica. Outcrops of inner-fan channel, middle-fan channel and interchannel, outer-fan lobe, fan-fringe, and basin-plain facies associations indicate that the depositional model of Mutti and Ricci Lucchi for mixed-sediment deep-sea fans can be used. The original fan had a radius of 30 to 50 km.

  13. Quantitative studies of hydrocarbon loss of the Silurian bitumen sandstone in the Tarim Basin

    Institute of Scientific and Technical Information of China (English)


    The evolution of Tarim Basin experienced several tectonic movements,of which Caledonian movement caused a serious damage to reservoirs of Silurian. The earlier reservoirs size and the later hydrocarbon loss are two key factors to exploration prospect of Silurian. On the basis of net thickness of bituminous sandstone and recovery coefficient of crude oil converting to bitumen,the scale of the hydrocarbon loss of palaeo-accumulation in bitumen sandstone of Silurian was calculated (86.30×108t). The deter-mination of net thickness of bitumen sandstone was completed mainly by several methods,such as physical property demarcation,observing lithology,grains with oil inclusion (GOI) technology,and quantitative grains fluorescence (QGF) technology. The samples of black sandstone and white sand-stone were collected and compared by means of the methods mentioned above. The results showed that there was little hydrocarbon,or none,in the white sandstone. The recovery coefficient was ob-tained by the analyses of plentiful physical parameters of crude oil and bitumen sandstone,based on the hypothesis that nonhydrocarbon compounds and bitumen were invariable in the process of bitu-men forming. The calculated result,which is more scientific and actual,indicates the exploration pros-pect is more promising in Silurian of the Tarim Basin.

  14. A pterodactyloid pterosaur from the Upper Cretaceous Lapurr sandstone, West Turkana, Kenya

    Directory of Open Access Journals (Sweden)

    Patrick M. O'Connor


    Full Text Available An isolated pterosaurian caudal cervical (~ postcervical vertebra was recovered from the Upper Cretaceous Lapurr sandstone ofWest Turkana, northwestern Kenya. The vertebral centrum is short, wide, and dorsoventrally compressed. Although the specimen is lightly built similar to most pterosaurs, it is here referred to Pterodactyloidea and tentatively to the Azhdarchidae in that it lacks pneumatic features on both the centrum and neural arch. This represents one of the few pterosaurs recovered from the entirety of Afro-Arabia, the first pterosaur recovered from the Cretaceous of East Africa, and, significantly, a specimen that was recovered from fluvial deposits rather than the near-shore marine setting typical of most pterosaur discoveries.Uma vértebra cervical caudal isolada de pterossauro (~ pós-cervical foi recuperada do Cretáceo Superior do arenito de Lapurr do Oeste de Turkana, noroeste do Quênia. O centro vertebral é curto, largo e comprimido dorsoventralmente. Embora o espécime seja leve como grande parte dos pterossauros, ele é aqui referido a Pterodactyloidea e tentativamente a Azhdarchidae no que diz respeito à ausência de características pneumáticas tanto no centro quanto no arco neural. Este representa um dos poucos pterossauros recuperados do conjunto Afro-Arábia, o primeiro pterossauro proveniente do Cretáceo do Leste da África e, significativamente, um espécime que foi recuperado de depósitos fluviais e não do cenário marinho próximo da costa típico da maioria das descobertas de pterossauros.

  15. Single-grain detrital-muscovite ages from Lower Cretaceous sandstones, Scotian Basin, and their implications for provenance

    Energy Technology Data Exchange (ETDEWEB)

    Reynolds, P.H.; Grist, A.M. [Dalhousie Univ., Halifax, NS (Canada). Dept. of Earth Sciences; Pe-Piper, G. [Saint Mary' s Univ., Halifax, NS (Canada). Dept. of Geology; Piper, D.J.W. [Geological Survey of Canada, Bedford Inst. of Oceanography, Dartmouth, NS (Canada). Atlantic Geoscience Center


    Detrital muscovite is relatively abundant in the Lower Cretaceous rocks of the Scotian Basin, where the deltaic sandstones form important gas reservoirs. This paper reported on a study that used the single-grain geochronology dating technique to re-examine the significance of muscovite as a detrital mineral in the Scotian Basin. The objective was to better understand the sources of sediments in the offshore reservoir sandstone and to identify sediment dispersal patterns. Information on the detrital petrology and sediment provenance of the Lower Cretaceous sandstone is important for exploration models and for determining diagenesis and reservoir quality. One hundred muscovite grains were dated from a transect of wells near Sable Island. An additional 17 grains were dated from the Naskapi N-30 well in the western part of the basin. In general, the muscovite ranges in age from ca. 420 to 240 Ma, suggesting that ages were not reset by post-depositional alteration. The principal sources were rocks that had experienced resetting during Alleghenian deformation and Late Triassic, earliest Jurassic rifting. According to the distribution of ages and mass balance calculations, the sources were primarily Meguma metasedimentary rocks on the inner Scotian Shelf. The age distribution at Naskapi N-30 is similar to that in the South Mountain batholith, except for some grains younger than 360 Ma that suggest an offshore source with Alleghenian resetting. This paper also provided evidence that the inner shelf was an erosional area during the Early Cretaceous. 59 refs., 2 tabs., 7 figs., 1 appendix.

  16. 塔里木盆地典型砂岩油气储层自生伊利石K-Ar同位素测年研究与成藏年代探讨%K-Ar Dating of Authigenic Illites and Its Applications to the Study of Hydrocarbon Charging Histories of Typical Sandstone Reservoirs in Tarim Basin, China

    Institute of Scientific and Technical Information of China (English)


    The Tarim Basin in China comprises eight sets of sandstone reservoirs, five of which are investigated in detail in this study. The main purpose of this study is to investigate the hydrocarbon charging histories of reservoirs by applying K-Ar dating of authigenic illites. The ages of authigenic illites from the Lower Silurian bituminous sandstones in the Central Uplift area range from 383.5 to 235.2 Ma, suggesting that the Silurian oil accumulations were formed from the late Caledonian till the late Hercynian. The ages of authigenic illites from the Upper Devonian Donghe Sandstone reservoirs range from 263.8 to 231.3 Ma, indicating that hydrocarbon accumulations within the Donghe sandstone were formed mainly in the late Hercynian. The authigenic illites ages from the Lower Jurassic Yangxia Group sandstones in the Yinan-2 gas reservoir (Yinan-2, Kuqa Depression) range from 28.1 to 23.9 Ma, suggesting that the initial hydrocarbon charging occurred in the Miocene. The ages of the authigenic illites from the Lower Cretaceous sandstones in the Akemomu gas field (Ake-1, Kashi Sag, Southwest Depression) range from 22.6 to 18.8 Ma, indicating a probable early oil accumulation or early migration of hydrocarbon within this area. The illites from the Paleogene sandstones in the Dina-2 gas reservoir (Dina-201, Kuqa Depression) have a detrital origin; they cannot be used to study the hydrocarbon charging histories. The ages of authigenic illites in the underlying Cretaceous sandstones in the same well (Dina-201)range from 25.5 to 15.5 Ma, indicating that hydrocarbon charging in this reservoir probably occurred within the Miocene.This study highlights the potential of applying K-Ar dating of authigenic illites to investigate the timing of hydrocarbon charging histories of the Tarim Basin reservoir sandstones.

  17. Evidence of Multi-Stage Hydrocarbon Charging and Biodegradation of the Silurian Asphaltic Sandstones in the Tarim Basin, China

    Institute of Scientific and Technical Information of China (English)



    Asphalts distributed widely in the Silurian sandstones of the Tarim Basin include dry asphalt, soft asphalt and heavy oil. These asphaltic sandstones underwent multi-episodic sedimentary and tectonic events, and their occurrence is diverse and complex, being mixed with normal oil usually. So far, very little work has been done on the asphaltic sandstone origin and hydrocarbon charging ages. After detailed study on the Silurian sandstones, the following highlights were obtained from the analytical results: distribution of the mixed asphalt, heavy oil and normal oil in the Silurian sandstones is the result of multi-stage hydrocarbon charging from the Lower Paleozoic marine source rocks; the characters of asphalts formed from oils of different charging ages are of difference; the most important process constraining.the asphaltic sandstone origin is thought to be biodegradation.

  18. The Upper Cretaceous Ostravice Sandstone in the Polish sector of the Silesian Nappe, Outer Western Carpathians

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    Cieszkowski Marek


    Full Text Available The Ostravice Sandstone Member was identified and described as a lithostratigraphic unit in the Polish part of the Outer Carpathians. This division occurs in the lowermost part of the Godula Formation, is underlain by variegated deposits of the Mazák Formation or directly by the Barnasiówka and Lhoty formations, and overlain by the Czernichów Member of the Godula Formation. Domination by thick- and very thick-bedded sandstones, conglomeratic sandstones and conglomerates rich in calcareous clasts, mostly of the Štramberk-type limestones, is typical for the Ostravice Sandstone Member. These deposits are widespread between the Moravskoslezské Beskydy Mountains in the Czech Republic and the Ciężkowice Foothills in Poland. The documentation of the Ostravice Sandstone Member occurrence as well as the petrological, sedimentological features, and inventory of the carbonate clasts are presented here.

  19. Relief-induced soil zones at the Cretaceous sandstone-mudstone contact in the Stolowe Mountains, SW Poland (United States)

    Kabala, Cezary; Waroszewski, Jaroslaw; Jezierski, Pawel


    Regolith translocation on mountain slope built of stratified rocks creates mixed or layered covers which may obliterate the actual transitions of rocks. The covers are seldom delineated on geological maps due to their insignificant thickness; however, enough large to influence the soil morphology and ecological functions. A toposequence of six soil sections situated at the contact of Cretaceous sandstone and mudstone was investigated to evaluate the influence of relief-position and morphological processes on slope cover formation, as well as soil and forest habitat arrangement. At least four distinct soil zones were distinguished in the 400 m long catena: (1) Arenosols and sand Regosols zone, on active fluvial cones and blocky covers directly below sandstone cliffs; (2) upper mid-slope zone of Podzols developed from sandstone-derived materials with periglacial features (solifluction) in the subsoil; (3) lower mid-slope and foot-slope zone of Stagnosols and Planosols with prolonged water stagnation over the impermeable subsoil developed from sandstone or mixed sandstone-mudstone regolith; excess of water is also the sign of mudstone bedrock that forces lateral water flow; and (4) toe-slope zone of Cambisols developed from the mudstone regolith. Past and present-day morphological processes have broadened the area mantled by sandstone-derived materials from upper-slope and created transitional materials that enhanced soil variability and multi-step zonality over the presumably sharp contact of sandstone and mudstone bedrocks. Financed in part by the Ministry of Science and Higher Education of Poland (project number: N N310 435938) and National Science Centre (project OPUS 2012/05/B/NZ9/03389). Lorz, C., Heller, K., Kleber, A. (2011): Stratification of the regolith continuum - a key property for processes and functions of landscapes. Z Geomorphol 55, 3: 277-292. Sauer, D., Felix-Heningsen, P. (2006): Saprolite, soils and sediments in the Rhenish Massif as records of

  20. Petrologic and isotopic data from the Cretaceous (Campanian) Blackhawk Formation and Star Point Sandstone (Mesaverde Group), Wasatch Plateau, Utah (United States)

    Fishman, Neil S.; Turner, Christine E.; Peterson, Fred


    The presence of discrete minerals associated with coal—whether (1) detrital or authigenic constituents of the coals or in thin mudstone or siltstone units interbedded with coals, or (2) authigenic phases that formed along cleats—might influence its utilization as an energy resource. The build-up of sintered ash deposits on the surfaces of heat exchangers in coal-fired power plants, due to the alteration of minerals during combustion of the coal, can seriously affect the functioning of the boiler and enhance corrosion of combustion equipment. In particular, the presence of sodium in coals has been considered a key factor in the fouling of boilers; however, other elements (such as calcium or magnesium) and the amount of discrete minerals burned with coal can also play a significant role in the inefficiency of and damage to boilers. Previous studies of the quality of coals in the Cretaceous (Campanian) Blackhawk Formation of the Wasatch Plateau, Utah, revealed that the sodium content of the coals varied across the region. To better understand the origin and distribution of sodium in these coals, petrologic studies were undertaken within a sedimentological framework to evaluate the timing and geochemical constraints on the emplacement of sodium-bearing minerals, particularly analcime, which previously had been identified in coals in the Blackhawk Formation. Further, the study was broadened to include not just coals in the Blackhawk Formation from various localities across the Wasatch Plateau, but also sandstones interbedded with the coals as well as sandstones in the underlying Star Point Sandstone. The alteration history of the sandstones in both formations was considered a key component of this study because it records the nature and timing of fluids passing through them and the associated precipitation of sodium-bearing minerals; thus, the alteration history could place constraints on the distribution and timing of sodium mineralization in the interbedded or

  1. Petrophysical evaluation of the hydrocarbon potential of the Lower Cretaceous Kharita clastics, North Qarun oil field, Western Desert, Egypt (United States)

    Teama, Mostafa A.; Nabawy, Bassem S.


    Based on the available well log data of six wells chosen in the North Qarun oil field in the Western Desert of Egypt, the petrophysical evaluation for the Lower Cretaceous Kharita Formation was accomplished. The lithology of Kharita Formation was analyzed using the neutron porosity-density and the neutron porosity-gamma ray crossplots as well as the litho-saturation plot. The petrophysical parameters, include shale volume, effective porosity, water saturation and hydrocarbon pore volume, were determined and traced laterally in the studied field through the iso-parametric maps. The lithology crossplots of the studied wells show that the sandstone is the main lithology of the Kharita Formation intercalated with some calcareous shale. The cutoff values of shale volume, porosity and water saturation for the productive hydrocarbon pay zones are defined to be 40%, 10% and 50%, respectively, which were determined, based on the applied crossplots approach and their limits. The iso-parametric contour maps for the average reservoir parameters; such as net-pay thickness, average porosity, shale volume, water saturation and the hydrocarbon pore volume were illustrated. From the present study, it is found that the Kharita Formation in the North Qarun oil field has promising reservoir characteristics, particularly in the northwestern part of the study area, which is considered as a prospective area for oil accumulation.

  2. Sandstone provenance and diagenesis in relation to Late Cretaceous regional depositional systems and paleogeography, Sacramento Basin, CA

    Energy Technology Data Exchange (ETDEWEB)

    Mertz, K.A. Jr. (Miami Univ., Oxford, OH (USA)); Nilsen, T.H. (Applied Earth Technology, Inc., Redwood City, CA (USA))


    Petrographic modal analyses of sandstone samples from the Upper Cretaceous Guinda, Forbes, Kone, Marsh Creek, Chico, Starky, Winters, and Mokelumne River formations of the Sacramento basin reveal that samples are dominated by plutoniclastic and volcaniclastic detritus, have intermediate plagioclase-to-total=feldspar ratios (0.48-0.65), and have high but variable L{sub v}/L ratios (0.51-0.80). Forbes/Kione sandstones, in comparison to Starkey/Winters samples, have higher proportions of volcaniclastic (plagioclase) to plutoniclastic (Q{sub m}, K) detritus and higher W{sub p}/total Q and L{sub m}/L{sub v} ratios. The Chico Formation, like the Starkey/Winters, is dominated by plutoniclastic material; in comparison to Forbes/Kione samples, the Chico has higher total lithic values (L{sub t}), especially in the L{sub m} fraction. These data strongly support derivation of the sands from the Cordilleran magmatic arc system to the north and east. Sandstones from the Chico, Starkey, Winters, and Mokelumne River formations were derived primarily from the dissected Sierran magmatic arc complex to the east, with a minor but significant secondary source in foothill belt metamorphic complexes. Forbes and Kione sandstones, in contrast, appear to have been derived from the Idaho Batholith and Blue Mountain regions of Idaho/Oregon to the north and northeast. When corrections are applied to account for significant diagenetic dissolution of plagioclase and compactional alteration of lithic fragments (especially L{sub v}), the dissected or transitional arc provenance for most samples is strengthened. Modal data and paleogeographic reconstructions suggest that during the early and middle Campanian, most detritus in the Sacramento basin was derived from the north/northeast (erosion of the Idaho batholith arc system), reflecting southward progradation of the Kion/Forbes delta-submarine fan system into the longitudinal forearc basin.

  3. Stratigraphy and petroleum potential of Trout Creek and Twentymile sandstones (Upper Cretaceous), Sand Wash Basin, Colorado

    Energy Technology Data Exchange (ETDEWEB)

    Siepman, B.R.


    The Trout Creek and Twentymile Sandstones (Mesaverde Group) in Moffat and Routt Counties, Colorado, are thick, upward-coarsening sequences that were deposited along the western margin of the Western Interior basin during Campanian time. These units trend northeast-southwest and undergo a facies change to coal-bearing strata on the northwest. Surface data collected along the southeastern rim of the Sand Wash basin were combined with well-log data from approximately 100 drill holes that have penetrated the Trout Creek or Twentymile in the subsurface. The sandstones exhibit distinctive vertical profiles with regard to grain size, sedimentary structures, and biogenic structures. A depositional model that incorporates the key elements of the modern Nile River (northeast Africa) and Nayarit (west-central Mexico) coastal systems is proposed for the Trout Creek and Twentymile sandstones and associated strata. The model depicts a wave-dominated deltaic, strand-plain, and barrier-island system. Depositional cycles are asymmetrical in cross section as they are largely progradational and lack significant transgressive deposits. Source rock-reservoir rock relationships are ideal as marine shales underlie, and coal-bearing strata overlie sheetlike reservoir sandstones. Humic coal, the dominant source of Mesaverde gas, generates major quantities of methane upon reaching thermal maturity. Existing Mesaverde gas fields are largely structural traps, but stratigraphic and combination traps may prove to be equally important. The sparsely drilled deeper part of the basin warrants testing as large, overpressured-gas accumulations in tight-sandstone reservoirs are likely to be found.

  4. Hydrocarbon Seepage during the Boreal Base Cretaceous Hot Shale Event (United States)

    Hammer, Ø.; Hryniewicz, K.; Nakrem, H. A.; Little, C.


    We have identified a number of carbonate bodies interpreted as seep-related from near the Jurassic-Cretaceous boundary in Svalbard, arctic Norway. The paleoseeps discovered so far occur over 50 km along strike, representing a seepage field of considerable extent. Ammonites indicate a base Cretaceous (Late Volgian to Late Ryazanian) age. The carbonate bodies are highly fossiliferous, with a very diverse fauna consisting mainly of normal-marine species but also seep-restricted taxa. Carbonate d13C isotopes reach -46‰, which, considering mixture with seawater-derived carbon, is interpreted as indicating a biogenic methane source. It is of interest to note the correlation of this paleoseepage with an episode of extremely high burial of organic matter near the Jurassic-Cretaceous boundary, noted both in Svalbard (top Slottsmøya Member of the Agardhfjellet Formation), in the Barents Sea (Hekkingen Formation) and in the North Sea (Mandal Formation), possibly providing a shallow source for biogenic gas. Together with near contemporaneous events in the Boreal Realm such as ongoing rifting, the base Cretaceous unconformity, the Mjølnir meteorite impact and a possible minor extinction event, these finds contribute to the impression of the Jurassic-Cretaceous boundary as a highly dynamic and interesting time in the North Atlantic area.

  5. Diagenetic characteristics and reservoir quality of the Lower Cretaceous Biyadh sandstones at Kharir oilfield in the western central Masila Basin, Yemen (United States)

    Hakimi, Mohammed Hail; Shalaby, Mohamed Ragab; Abdullah, Wan Hasiah


    The Lower Cretaceous Biyadh Formation in the Masila Basin is an important hydrocarbon reservoir. However, in spite of its importance as a reservoir, published studies on the Biyadh Formation more specifically on the diagenesis and relate with reservoir quality, are limited. Based on core samples from one well in the Kharir oilfield, western central Masila Basin, this study reports the lithologic and diagenetic characteristics of this reservoir. The Biyadh sandstones are very fine to very coarse-grained, moderate to well sorted quartzarenite and quartzwacke. The diagenetic processes recognized include mechanical compaction, cementation (carbonate, clay minerals, quartz overgrowths, and a minor amount of pyrite), and dissolution of the calcite cement and feldspar grains. The widespread occurrences of early calcite cement suggest that the Biyadh sandstones lost a significant amount of primary porosity at a very early stage of its diagenetic history. Based on the framework grain-cement relationships, precipitation of the early calcite cement was either accompanied or followed by the development of part of the pore-lining and pore-filling clay cements. Secondary porosity development occurred due to partial to complete dissolution of early calcite cement and feldspar grains. In addition to calcite, several different clay minerals including kaolinite and chlorite occur as pore-filling and pore-lining cements. Kaolinite largely occurs as vermiform and accelerated the minor porosity loss due to pore-occlusion. Chlorite coating grains helps to retain primary porosity a by retarding the envelopment of quartz overgrowths. Porosity and permeability data exhibit good inverse correlation with cement. Thus, reservoir quality is controlled by pore occluding cement. Diagenetic history of the Biyadh sandstones as established here is expected to help better understanding and exploitation of this reservoir. The relation between diagenesis and reservoir quality is as follows: the

  6. Diagenesis and reservoir properties of Cretaceous-Lower Tertiary sandstones: the GANT-1 well, western Nuussuaq, central West Greenland

    Energy Technology Data Exchange (ETDEWEB)

    Kierkegaard, Thomas


    The main purpose of this study is to describe the diagenetic alterations occurring in the Cretaceous to Lower Paleocene sedimentary succession of the GANT-1 well, and to determine the diagenetic and detrital factors which control present porosity and permeability. The GANT-1 well is located on north-western Nuussuaq, central West Greenland. The West Greenland margin is a continental margin subdivided into linked basins where Cretaceous to Lower Tertiary and probably older sediments have been deposited. In the Nuussuaq area these sediments are overlain by a succession of Early Tertiary basaltic volcanic rocks which reaches a combined thickness of around 2-2.5 km. Although the reservoir properties of the sandstone intervals in the GANT-1 and GANE-1 wells are generally relatively poor, it is suggested that moderate to good properties may be found in certain intervals within the Maastrichtian-Paleocene succession. However, the reason for the locally enhanced reservoir properties in GANT-1 was not clarified by this study due to the lack of regional petrographical data. (EG) EFP-96. 41 refs., 3 maps

  7. Isotopic composition of salt efflorescence from the sandstone castellated rocks of the Bohemian Cretaceous Basin (Czech Republic) (United States)

    Schweigstillová, Jana; Přikryl, Richard; Novotná, Miroslava


    The origin of sulphates in sulphate-rich efflorescences on quartz sandstones with a clay matrix, exposed in rural areas of the Czech Republic is interpreted, based upon an isotopic study of S and O. Sulphates such as gypsum and/or alums exhibit δ34S ranging from +1.3 to +6.1‰ and δ18O from +5.3 to +8.8‰. The low variability of S and O isotopes indicates a common source of the sulphur and a similar mode of sulphate formation. Atmospheric sulphates with a similar isotopic signature occur in the area, due to the combustion of sulphurous coal in power plants, located a few tens of kilometres from the sampling points. The sulphates crystallize from supersaturated pore waters that represent atmospheric precipitation, rich in sulphates, having percolated through the porous sandstone system. The previously proposed model of efflorescence growth (that it is due to the oxidation of pyrite) can be excluded, due to both the rare occurrence of pyrite and also to its different isotopic signature (δ34S about -22‰). Although gypsum prevails in the central and eastern part of the studied area, the north and north-west of the Bohemian Cretaceous Basin (the most polluted region) exhibits a significant presence of alums (NH4 + or K+-NH4 +-rich). Formation of alums can be explained by the partial dissolution of clay minerals or feldspars present in the sandstone matrix. Release of alumina from these phases is facilitated by the low pH of the precipitation (pH 4-4.5) and also locally by organic acids, traces of which were found in the studied efflorescences by the use of infrared spectroscopy.

  8. A condensed middle Cenomanian succession in the Dakota Sandstone (Upper Cretaceous), Sevilleta National Wildlife Refuge, Socorro County, New Mexico (United States)

    Hook, Stephen C.; Cobban, William A.


    The upper part of the Dakota Sandstone exposed on the Sevilleta National Wildlife Refuge, northern Socorro County, New Mexico, is a condensed, Upper Cretaceous, marine succession spanning the first five middle Cenomanian ammonite zones of the U.S. Western Interior. Farther north in New Mexico these five ammonite zones occur over a stratigraphic interval more than an order of magnitude thicker. The basal part of this marine sequence was deposited in Seboyeta Bay, an elongate east-west embayment into New Mexico that marked the initial transgression of the western shoreline of the Late Cretaceous seaway into New Mexico. The primary mechanism for condensing this section was nearshore, submarine erosion, although nondeposition played a minor role. The ammonite fossils from each zone are generally fragments of internal molds that are corroded on one side, indicating submarine burial, erosion of the prefossilized steinkern, and corrosion on the sea floor. In addition, the base of the condensed succession is marked by a thin bed that contains abundant, white-weathering, spherical to cylindrical phosphate nodules, many of which contain a cylindrical axial cavity of unknown origin. The nodules lie on the bedding surface of the highly burrowed, ridge-forming sandstone near the top of the Dakota and occur in the overlying breccia. The breccia consists of rip-up clasts of sandstone and eroded internal molds of the ammonite Conlinoceras tarrantense, the zonal index for the basal middle Cenomanian. The nodules below the breccia imply a time of erosion followed by nondeposition or sediment bypass during which the phosphatization occurred. The breccia implies a time of submarine erosion, probably storm-related. Remarkably, this condensed succession and the basal part of the overlying Mancos Shale tongue contain one of the most complete middle Cenomanian ammonite sequences in the U.S. Western Interior. Five of the six ammonite zones that characterize the middle Cenomanian of the

  9. Effect of hydrocarbon to nuclear magnetic resonance (NMR) logging in tight sandstone reservoirs and method for hydrocarbon correction (United States)

    Xiao, Liang; Mao, Zhi-qiang; Xie, Xiu-hong


    It is crucial to understand the behavior of the T2 distribution in the presence of hydrocarbon to properly interpret pore size distribution from NMR logging. The NMR T2 spectrum is associated with pore throat radius distribution under fully brine saturated. However, when the pore space occupied by hydrocarbon, the shape of NMR spectrum is changed due to the bulk relaxation of hydrocarbon. In this study, to understand the effect of hydrocarbon to NMR logging, the kerosene and transformer oil are used to simulate borehole crude oils with different viscosity. 20 core samples, which were separately drilled from conventional, medium porosity and permeability and tight sands are saturated with four conditions of irreducible water saturation, fully saturated with brine, hydrocarbon-bearing condition and residual oil saturation, and the corresponding NMR experiments are applied to acquire NMR measurements. The residual oil saturation is used to simulate field NMR logging due to the shallow investigation depth of NMR logging. The NMR spectra with these conditions are compared, the results illustrate that for core samples drilled from tight sandstone reservoirs, the shape of NMR spectra have much change once they pore space occupied by hydrocarbon. The T2 distributions are wide, and they are bimodal due to the effect of bulk relaxation of hydrocarbon, even though the NMR spectra are unimodal under fully brine saturated. The location of the first peaks are similar with those of the irreducible water, and the second peaks are close to the bulk relaxation of viscosity oils. While for core samples drilled from conventional formations, the shape of T2 spectra have little changes. The T2 distributions overlap with each other under these three conditions of fully brine saturated, hydrocarbon-bearing and residual oil. Hence, in tight sandstone reservoirs, the shape of NMR logging should be corrected. In this study, based on the lab experiments, seven T2 times of 1ms, 3ms, 10ms, 33ms

  10. Depositional sequence stratigraphy and architecture of the cretaceous ferron sandstone: Implications for coal and coalbed methane resources - A field excursion (United States)

    Garrison, J.R.; Van Den, Bergh; Barker, C.E.; Tabet, D.E.


    This Field Excursion will visit outcrops of the fluvial-deltaic Upper Cretaceous (Turonian) Ferron Sandstone Member of the Mancos Shale, known as the Last Chance delta or Upper Ferron Sandstone. This field guide and the field stops will outline the architecture and depositional sequence stratigraphy of the Upper Ferron Sandstone clastic wedge and explore the stratigraphic positions and compositions of major coal zones. The implications of the architecture and stratigraphy of the Ferron fluvial-deltaic complex for coal and coalbed methane resources will be discussed. Early works suggested that the southwesterly derived deltaic deposits of the the upper Ferron Sandstone clastic wedge were a Type-2 third-order depositional sequence, informally called the Ferron Sequence. These works suggested that the Ferron Sequence is separated by a type-2 sequence boundary from the underlying 3rd-order Hyatti Sequence, which has its sediment source from the northwest. Within the 3rd-order depositional sequence, the deltaic events of the Ferron clastic wedge, recognized as parasequence sets, appear to be stacked into progradational, aggradational, and retrogradational patterns reflecting a generally decreasing sediment supply during an overall slow sea-level rise. The architecture of both near-marine facies and non-marine fluvial facies exhibit well defined trends in response to this decrease in available sediment. Recent studies have concluded that, unless coincident with a depositional sequence boundary, regionally extensive coal zones occur at the tops of the parasequence sets within the Ferron clastic wedge. These coal zones consist of coal seams and their laterally equivalent fissile carbonaceous shales, mudstones, and siltstones, paleosols, and flood plain mudstones. Although the compositions of coal zones vary along depositional dip, the presence of these laterally extensive stratigraphic horizons, above parasequence sets, provides a means of correlating and defining the tops

  11. Field tests for immobilisation of pollutants in leached upper cretaceous sandstone; Feldversuche zur Schadstoffimmobilisierung in gelaugtem Quadersandstein

    Energy Technology Data Exchange (ETDEWEB)

    Ziegenbalg, G. [TU Bergakademie Freiberg (Germany). Inst. fuer Technische Chemie; Schreyer, J.; Jenk, U. [Wismut GmbH, Chemnitz (Germany)


    The underground, in situ leaching process with diluted sulphuric acid used in the former Koenigstein uranium ore mine of Wismut GmbH led to large panels contaminated by acid solutions. Flooding of the mine will be attended by long-term occurrence of acid water polluted by heavy metals, which should be treated. Hence the use of in-situ immobilisation processes for reduction of pollutants is of particular interest. Such a process must lead to formation of minerals with long-term stability and must not be associated with the additional introduction of pollutants. A process meeting these requirements is based on the use of BaSO{sub 4}-supersaturated solutions, which can be prepared by the mixing of Ba(OH){sub 2} solutions with dilute sulphuric acid in the presence of a precipitation inhibitor. If contaminated areas are treated with BaSO{sub 4}-supersaturated solutions, a crystallisation process leading to formation of slightly soluble BaSO{sub 4} layers takes place in the flow paths. These shield underlying minerals from leaching processes. At the same time secondary minerals such as hydroxides or hydroxysulphates, which bring about additional pollutant fixing, are formed. Comprehensive laboratory and technical tests as well as a field test in the Koenigstein mine revealed the efficiency of the process and proved its advantageous suitability for the clean-up of leached upper cretaceous sandstone. (orig.)

  12. Petrography and diagenesis of Gomo member sandstones - Candeias Formation (lower cretaceous) Rio do Buoil field, Reconcavo Basin; Petrografia e diagenese dos arenitos do Membro Gomo - Formacao Candeias (Cretaceo Inferior) no Campo de Rio do Bu, Bacia do Reconcavo

    Energy Technology Data Exchange (ETDEWEB)

    Mato, Luiz F.; Souza, Edson M. [PETROBRAS, BA (Brazil). Distrito de Exploracao


    Characteristics, textural and compositional aspects, analyse the provenance and diagenetic evolution of the Gomo Member/Candeias Formation sandstones (Lower Cretaceous) in the Rio do Bu oil field, Reconcavo Basin, are discussed. Studies of sandstone petrography, shales and carbonates associated, diagenetic sequence, rifts fractures and cementation characterization, are also analyzed. 17 figs., 2 tabs., 19 refs

  13. Effect of Water Washing on Hydrocarbon Compositions of Petropleum Sandstone Reservoir Rocks in Tarim Basin,NW China

    Institute of Scientific and Technical Information of China (English)

    张敏; 张俊


    Gross compositions and distribution of saturated and aromatic hydrocarbons in Carboniferous sandstone reservoire rocks in oil and water zones for Tzhong-10 well of the Zhongyang Uplift in the Tarim Basin were studied in dteail by means of Rock-Eval Pyrolysis,thin-chromatograph-flame ionization detection(TLC-FID),gas chromatography,gas chromatography-mass spectrometry.The results suggest that the gross composition of reservoir hydrocarbons between the oil zone and the water zone show significant differences,Water wahing has a dramatic effect on saturated hydrocarbon blomarkers,especially drimane series compounds,Drimane series compounds in the water zone have been depleted completely.However,the contents of tricyclic iterpanes and pentacyclic triterpanes tend to decrease slightly,but the water-zone reservoir hydrocarbons contian a large amount of gammacerane.This suggests that gammacerane be more resistant to water washing than diterpanes and homohopanes.The contents of pregnane,homopregrane,diasteranes relastively decrease as a result of water washing.Water washing has a noticeable effect on polycyclic aromatic hydrocarbon compounds,especially aromatic sulfur compounds,and the contents of dibenzothiophene series compounds and benzonaplyiothipophene decrease significantly as a result of water washing.However,the conterts of bicyclic and tricyclic aromatic hydrocarbons decrase slightly and those of tetracyclic and pentacyclic aromatic hydrocarbons,especially benzofluoranthene and benzopyrenes,increase markedly owing to adecrease in light aromatie hydrocarbons as a result of water washing.

  14. Controls on the Lower Cretaceous Punt Sandstone Member, a massive deep-water clastic deposystem, Inner Moray Firth, UK North Sea

    Energy Technology Data Exchange (ETDEWEB)

    Argent, J.D.; Stewart, S.A. [Amerada Hess Ltd., London (United Kingdom); Underhill, J.R. [University of Edinburgh (United Kingdom). Dept. of Geology and Geophysics


    Interpretation of high-quality seismic data, constrained by exploration wells, provides insights into controls on the stratigraphic architecture and deep-water sedimentary processes that governed deposition of the Lower Cretaceous Punt Sandstone Member in the Inner Moray Firth Basin. We suggest a model of deposition in which sediment provenance from the north and west progressively filled depositional accommodation in proximal depocentres before spilling into more distal areas via linear, confined and incised channel complexes. As well as giving important clues into post-rift depositional processes in the basin, and a well-imaged ancient analogue for the deposition of massive deep-water sands, the seismic and stratigraphic data may also provide important insights into factors governing the poorly imaged Lower Cretaceous sands in neighbouring basins of the North Sea. (Author)

  15. Cretaceous to miocene palaeogegraphic evolution of Turkey: implications for hydrocarbon potential

    Energy Technology Data Exchange (ETDEWEB)

    Gorur, N. [Tubitak Mam, Gebze (Turkey)


    The Cretaceous to Miocene palaeogeographic development of Turkey in general reflects the evolution of the various oceanic branches of Neo-Tethys together with interactions between the Laurasian and Gondwanan margins. At the beginning of the Cretaceous, the first-order palacotectonic units which make up present-day Turkey either formed parts of these supercontinents or were isolated continental blocks within the Neo-Tethys. In Aptian to Albian times, north-dipping subduction commenced along the southern margins of these units and resulted in the development of magmatic arcs and arc-related sedimentary basins. Coeval with the start of subduction, large-scale ophiolite abduction occurred on the units' passive margins. Terminal closure of the oceans' branches took place between the latest Cretaceous and the Miocene, forming the Anatolian orogenic collage whose outline defines present-day Turkey. Post-collisional intra-continental convergence continued until the late Miocene and resulted in north-south shortening of the collage. This shortening led to internal imbrication, thrusting and crustal thickening. It forced the Anatolian landmass westwards, away from east Anatolia where there has been continuous north-south compression since the Miocene between Laurasia and the Arabian Platform. Both the continental and the oceanic palaeotectonic units pose significant problems regarding their original geometry, size, depth, extent, contact relations, motion paths, subduction polarity, stratigraphy and timing of formation. Clarification of these issues is essential if the units' original paleogeographic relationships with respect to Neo-Tethys are to be reconstructed. This paper reviews some of these problems with the aid of a number of palinspastic and non-palinspastic maps. These maps are intended to provide a basis for evaluating the hydrocarbon potential of Turkey. (author)

  16. Characteristics of deltaic deposits in the Cretaceous Pierre Shale, Trinidad Sandstone, and Vermejo Formation, Raton Basin, Colorado. (United States)

    Flores, R.M.; Tur, S.M.


    Detailed facies analyses of closely spaced measured surface sections in the Trinidad and adjacent areas of Colorado reflect deposition in the river-influenced delta. That this deltaic system was accompanied by abandonment of subdeltas is indicated by a destructional-deltaic facies of heavily bioturbated, carbonaceous sandstones, siltstones, and shales best recorded in the delta front deposits of the Trinidad Sandstone. Coal accumulation of the Vermejo deposits nevertheless remained primarily controlled by persistent organic sedimentation in interdistributary backswamps. These backswamps, which accumulated thick, lenticular coals, were formed during the normal constructional phase of the delta plain. -from Authors

  17. Ferroan dolomite cement in Cambrian sandstones: burial history and hydrocarbon generation of the Baltic sedimentary basin

    DEFF Research Database (Denmark)

    Sliaupa, S.; Cyziene, J.; Molenaar, Nicolaas


    The conditions and timing of carbonate cementation in Cambrian sandstones of the Baltic sedimentary basin were determined by oxygen and carbon stable isotope and chemical data in combination with optical and cathodoluminescence petrographic studies. Studied samples represent a range in present...

  18. Environmental-stratigraphic cross sections of the Cretaceous Fox Hills Sandstone and Hell Creek Formation and Paleocene Fort Union Formation, Richland and Roosevelt Counties, Montana (United States)

    Flores, R.M.; Lepp, C.L.


    This study was conducted to determine the stratigraphic, lithofacies, and deopsitional relationships of the Cretaceous Fox Hills Sandstone and Hell Creek Formation and The Paleocene Fort Union Formation. These relationships, shown in sections A-A', B-B', C-C', and D-D', we established form nearly continuous exposures in the Missouri River valley in Richland and Roosevelt Counties, Mont. The river valley topography is characterized by badlands, which permitted detailed description and construction of the stratigraphic framework of the formations within a 30-mi-long belt of exposures paralleling the Missouri River. This area of study is on the western flank of the Williston Basin and east of the Poplar Dome. The latter structure imparted a northeasterly regional dip to the rocks, which averages 25 ft per mi and is as much as 100 ft per mi according to Spencer (1980). The regional dip resulted in exposure of older rocks (Cretaceous) in the west to younger rocks (Tertiary) in the east. 

  19. Morphostructural record of iron deposits in paleosols, cretaceous Nubia Sandstone of Lake Naser basin, Egypt, Western Desert, Egypt

    Directory of Open Access Journals (Sweden)

    S.M. Salem


    Full Text Available The use of processed Landsat ETM + images and the application of geomorphotectonic concepts supplemented by extensive geological field work enabled the effective record of iron occurrences in the area located to the west of Lake Nasser. Three clearly newly differentiated landforms are evaluated for the possible presence of iron occurrences. Each landform is controlled by a specific tectonic environment and includes one of the three stratigraphic formations hosting iron deposits in the area. These landforms are: Area 1 (Kurkur landform, including plunging anticlines and domes affecting the Abu Aggag Formation. This formation is unconformably overlain by horizontal sandstone beds belonging to the Temsah Formation. The unconformity surface includes paleosols rich in limonite, crystallized gypsum in the form of roses and clay minerals. Area 2 (Tushka landform extends to the south of the Allaqi fault. The area includes yardangs carved in horizontal sandstone beds interstratified with some hematite bed, in addition to several fragments of hematite and magnetite as wadi deposits and desert varnish. Area 3 (Abu Simbel landform includes conical hills constituted by flattened horizontal beds belonging to the El Burg Formation. Each hill is capped by thick hematite/magnetite beds extending from Tushka to the border with Sudan. The Nubia Sandstone, here, includes three formations, namely: the Abu Aggag, Temsah, and Um Baramil.

  20. Geochemical characteristics of sandstones from Cretaceous Garudamangalam area of Ariyalur, Tamilnadu, India: Implications of provenance and tectonic setting

    Indian Academy of Sciences (India)

    Babu K


    The Trichinopoly Group (later redesignated as Garudamangalam) has unconformable relationship with underlying Uttatur Group and is divided into lower Kulakanattam Formation and upper Anaipadi Formation. These calcareous sandstones are analysed major, trace and rare earth elements (REEs) to find out CIA, CIW, provenance and tectonic setting. The silica content of fossiliferous calcareous sandstone show wide variation ranging from 12.93 to 42.56%. Alumina content ranged from 3.49 to 8.47%. Higher values of Fe2O3 (2.29–22.02%) and low MgO content (0.75–2.44%) are observed in the Garudamangalam Formation. CaO (23.53–45.90) is high in these sandstones due to the presence of calcite as cementing material. Major element geochemistry of clastic rocks (Al2O3 vs. Na2O) plot and trace elemental ratio (Th/U) reveal the moderate to intense weathering of the source rocks. The Cr/Zr ratio of clastic rocks reveal with an average of 1.74 suggesting of felsic provenance. In clastic rocks, high ratios of ΣLREE/ΣHREE, La/Sc, Th/Sc, Th/Co, La/Co and low ratios of Cr/Zr, and positive Eu anomaly ranges from (Eu/Eu* = 1.87–5.30) reveal felsic nature of the source rocks.

  1. Structural and microstructural evolution of fault zones in Cretaceous poorly lithified sandstones of the Rio do Peixe basin, Paraiba, NE Brazil (United States)

    Balsamo, Fabrizio; Nogueira, Francisco; Storti, Fabrizio; Bezerra, Francisco H. R.; De Carvalho, Bruno R.; André De Souza, Jorge


    In this contribution we describe the structural architecture and microstructural features of fault zones developed in Cretaceous, poorly lithified sandstones of the Rio do Peixe basin, NE Brazil. The Rio do Peixe basin is an E-W-trending, intracontinental half-graben basin developed along the Precambrian Patos shear zone where it is abutted by the Porto Alegre shear zone. The basin formed during rifting between South America and Africa plates and was reactivated and inverted in a strike-slip setting during the Cenozoic. Sediments filling the basin consist of an heterolithic sequence of alternating sandstones, conglomerates, siltstone and clay-rich layers. These lithologies are generally poorly lithified far from the major fault zones. Deformational structures in the basin mostly consist of deformation band-dominated fault zones. Extensional and strike-slip fault zones, clusters of deformation bands, and single deformation bands are commonly well developed in the proximity of the basin-boundary fault systems. All deformation structures are generally in positive relief with respect to the host rocks. Extensional fault zones locally have growth strata in their hangingwall blocks and have displacement generally view, they are organized in anastomosed segments with high connectivity. They strike E-W to NE-SW, and typically consist of wide fault cores (narrow shear bands, in which bedding is transposed into foliation imparted by grain preferred orientation. Microstructural observations show negligible cataclasis and dominant non-destructive particulate flow, suggesting that extensional fault zones developed in soft-sediment conditions in a water-saturated environment. Strike-slip fault zones commonly overprint the extensional ones and have displacement values typically lower than about 2 m. They are arranged in conjugate system consisting of NNW-SSE- and WNW-ESE-trending fault zones with left-lateral and right-lateral kinematics, respectively. Compared to extensional

  2. Jurassic and Cretaceous clays of the northern and central North Sea hydrocarbon reservoirs reviewed

    Energy Technology Data Exchange (ETDEWEB)

    Wilkinson, M.; Haszeldine, R.S.; Fallick, A.E.


    The principal clays of the northern and central North Sea are illite (sometimes with interlayered smectite) and kaolin. Chlorite is only locally important. Although it has been proposed that kaolin within North Sea sandstones is detrital in origin, the majority of workers have concluded that it is authigenic, largely the product of feldspar alteration. Kaolin is found within a wide range of sedimentary settings (and within shales) apparently defying the notion that kaolin is an indicator of meteoric water deposition. Within sandstones, the earliest authigenic kaolin has a vermiform morphology, the distribution of which is controlled by the availability of detrital mica to act as a nucleus, and the composition of the post-depositional porewaters. This vermiform kaolin formed in meteoric water, the presence of which is easily accounted for below sub-aerial exposure surfaces in non-marine formations, and below unconformities over marine units. In fully marine sands, and even marine shale units, kaolin still occurs. It has therefore been suggested that even these locations have been flushed with meteoric water. Early vermiform kaolin recrystallizes to a more blocky morphology as burial proceeds, at least in the Brent Group. Blocky kaolin has been reported as growing before, synchronously with, and after the formation of quartz overgrowths, though oxygen isotope studies support low-temperature growth, pre-quartz. Blocky kaolin may form during meteoric flushing associated with lower Cretaceous uplift and erosion, though it is found in fault blocks that are thought to have remained below sea level. Here, the kaolin may form in stagnant meteoric water, relics of the post-depositional porewater. It has also been proposed that the blocky kaolin grew in ascending basinal waters charged with carboxylic acids and CO{sub 2}, though this hypothesis is not supported by stable oxygen isotope data. Some of the blocky kaolin is dickite, the stable polymorph above 100{sup o}C. Fibrous

  3. Evaluation of bio-molecular signatures and hydrocarbon potential of upper Cretaceous shale, NE Nigeria (United States)

    Boboye, Olugbenga A.; Nzegwu, Uche A.


    The Bornu Basin is a sector of the Chad Basin located in the northeastern part of Nigeria, occupying about one-tenth of total area in Chad Basin. Twenty-eight representative shale cutting samples retrieved from Tuma-1, Sa-1 and Albarka-1 exploratory wells were analyzed. Seventeen shale samples systematically selected from Gongila, Fika Shale and Chad Formations were subjected to Total Organic Content (TOC), Rock-Eval pyrolysis, Soluble Organic Matter, Liquid Chromatography, Gas Chromatography and Gas Chromatography/Mass Spectrometry analyses. This is to characterize and assess the potential capability of the shale units. The results showed that TOC of the Coniacian-Paleocene shale units exceed the threshold (0.5 wt%) needed for petroleum generation. This classifies it as potential source beds. Evidence from biomarkers indicates a preponderance of marine organic matter with subordinate terrigenous input. The quantity of gammacerane occurrence suggests normal saline environment. The presence of oleanane index indicates angiosperms input into Cretaceous-Tertiary source rock. C35/C34 homohopane ratio showed the anoxia development towards the center of the basin. C29ααα (20R)/C27ααα (20R) sterane ratio indicate the dominance of marine organic matter with subordinate terrigenous input. The 22S/(22S + 22R) ratio of C31 hopane have not reached equilibrium as evident by immaturity to early mature stages from diagnostic ratios of βα moretane/αβ hopane, Ts/(Ts + Tm), 28,30-bisnorhopanes/17α-hopanes, diasteranes/regular steranes, ααα steranes/αββ steranes and 20S/(20S + 20R) C29 regular steranes respectively. This is corroborated with the Rock-Eval indices showing immature to earlier mature kerogen within the Fika Formation. It consists preeminently of Type IV, with subordinate Type III. The prospect for hydrocarbon in this part of the basin is only fair to moderate with potential for gaseous rather than liquid hydrocarbon.

  4. A multidisciplinary approach to digital mapping of dinosaurian tracksites in the Lower Cretaceous (Valanginian–Barremian) Broome Sandstone of the Dampier Peninsula, Western Australia (United States)

    Hacker, Jorg M.; Zlot, Robert; Poropat, George; Bosse, Michael; Salisbury, Steven W.


    The abundant dinosaurian tracksites of the Lower Cretaceous (Valanginian–Barremian) Broome Sandstone of the Dampier Peninsula, Western Australia, form an important part of the West Kimberley National Heritage Place. Previous attempts to document these tracksites using traditional mapping techniques (e.g., surface overlays, transects and gridlines combined with conventional photography) have been hindered by the non-trivial challenges associated with working in this area, including, but not limited to: (1) the remoteness of many of the tracksites; (2) the occurrence of the majority of the tracksites in the intertidal zone; (3) the size and complexity of many of the tracksites, with some extending over several square kilometres. Using the historically significant and well-known dinosaurian tracksites at Minyirr (Gantheaume Point), we show how these issues can be overcome through the use of an integrated array of remote sensing tools. A combination of high-resolution aerial photography with both manned and unmanned aircraft, airborne and handheld high-resolution lidar imaging and handheld photography enabled the collection of large amounts of digital data from which 3D models of the tracksites at varying resolutions were constructed. The acquired data encompasses a very broad scale, from the sub-millimetre level that details individual tracks, to the multiple-kilometre level, which encompasses discontinuous tracksite exposures and large swathes of coastline. The former are useful for detailed ichnological work, while the latter are being employed to better understand the stratigraphic and temporal relationship between tracksites in a broader geological and palaeoecological context. These approaches and the data they can generate now provide a means through which digital conservation and temporal monitoring of the Dampier Peninsula’s dinosaurian tracksites can occur. As plans for the on-going management of the tracks in this area progress, analysis of the 3D data

  5. Mineralogical, geochemical and hydrocarbon potential of subsurface Cretaceous shales, Northern Western Desert, Egypt

    Directory of Open Access Journals (Sweden)

    D.A. Mousa


    Full Text Available Twenty four Cretaceous shale core samples of Gibb Afia-1, Betty-1, Salam-1X and Mersa Matruh-1 wells were mineralogically and geochemically studied using XRD, XRF and Rock Eval Pyrolysis. Kaolinite, smectite and illite are the main clay minerals in addition to rare chlorite, while the non-clay minerals include quartz, calcite, dolomite and rare siderite. The shales were derived through intensive chemical weathering of mafic basement and older sedimentary rocks. These sediments were deposited in a near-shore shallow marine environment with some terrestrial material input. The shales have poor to fair organic content. It is marginally to rarely mature.

  6. From Back-arc Drifting to Arc Accretion: the Late Jurassic-Early Cretaceous Evolution of the Guerrero Terrane Recorded by a Major Provenance Change in Sandstones from the Sierra de los Cuarzos, Central Mexico (United States)

    Palacios Garcia, N. B.; Martini, M.


    The Guerrero terrane composed of Middle Jurassic-Early Cretaceous arc assemblages, were drifted from the North American continental mainland during lower Early Cretaceous spreading in the Arperos back arc basin, and subsequently accreted back to the continental margin in the late Aptian. Although the accretion of the Guerrero terrane represents one of the major tectonic processes that shaped the southern North American Pacific margin, the stratigraphic record related to such a regional event was not yet recognized in central Mexico. Due to the Sierra de los Cuarzos is located just 50 km east of the Guerrero terrane suture belt, its stratigraphic record should be highly sensitive to first order tectonic changes and would record a syn-tectonic deposits related to this major event. In that study area, were identified two main Upper Jurassic-Lower Cretaceous clastic units. The Sierra de los Cuarzos formation represents the lowermost exposed stratigraphic record. Sedimentary structures, sandstones composition, and U-Pb detrital zircon ages document that the Sierra de los Cuarzos formation reflects a vigorous mass wasting along the margin of the North American continental mainland, representing the eastern side of the Arperos back arc basin. Sandstones of the Sierra de los Cuarzos formation are free from detrital contributions related to the Guerrero terrane juvenile sources, indicating that the Arperos Basin acted like an efficient sedimentological barrier that inhibited the influence of the arc massifs on the continental mainland deposits. The Sierra de los Cuarzos formation is overlain by submarine slope deposits of the Pelones formation, which mark a sudden change in the depositional conditions. Provenance analysis documents that sandstones from the Pelones formation were fed by the mafic to intermediate arc assemblages of the Guerrero terrane, as well as by quartz-rich sources of the continental mainland, suggesting that, by the time of deposition of the Pelones

  7. Sequential Extraction on Oil Sandstones from TZ401 Well——A Case Study on Filling History of Hydrocarbon Reservoir

    Institute of Scientific and Technical Information of China (English)

    Pan Changchun; Liu Dayong


    Sequential extraction was performed on two oil sandstones from the Upper Carboniferous oil columns of TZ401 well.The free oils of these two oil sandstones and a crude oil from the Lower Carboniferous oil column of this well have low ratios of C28/C27+C28+ C29) steranes and gammacerane/C31 hopanes,ranging of 0.11-0.16 and 0.09-0.15,respectively,similar to those from the Middle-Upper Ordovician source rock.However,these two ratios for the adsorbed and inclusion oils of these two oil sandstones are relatively high,ranging of 0.29-0.31 and 0.26-0.40,respectively,similar to those of the Cambrian-Lower Ordovician source rock.This result demonstrates that the initial oil charging the reservoirs was derived from the Cambrian-Lower Ordovician source rock,whereas the later charging oil was derived from the Middle--Upper Ordovician source rock.

  8. Reservoir assessment of the Nubian sandstone reservoir in South Central Gulf of Suez, Egypt (United States)

    El-Gendy, Nader; Barakat, Moataz; Abdallah, Hamed


    The Gulf of Suez is considered as one of the most important petroleum provinces in Egypt and contains the Saqqara and Edfu oil fields located in the South Central portion of the Gulf of Suez. The Nubian sandstone reservoir in the Gulf of Suez basin is well known for its great capability to store and produce large volumes of hydrocarbons. The Nubian sandstone overlies basement rocks throughout most of the Gulf of Suez region. It consists of a sequence of sandstones and shales of Paleozoic to Cretaceous age. The Nubian sandstone intersected in most wells has excellent reservoir characteristics. Its porosity is controlled by sedimentation style and diagenesis. The cementation materials are mainly kaolinite and quartz overgrowths. The permeability of the Nubian sandstone is mainly controlled by grain size, sorting, porosity and clay content especially kaolinite and decreases with increase of kaolinite. The permeability of the Nubian Sandstone is evaluated using the Nuclear Magnetic Resonance (NMR technology) and formation pressure data in addition to the conventional logs and the results were calibrated using core data. In this work, the Nubian sandstone was investigated and evaluated using complete suites of conventional and advanced logging techniques to understand its reservoir characteristics which have impact on economics of oil recovery. The Nubian reservoir has a complicated wettability nature which affects the petrophysical evaluation and reservoir productivity. So, understanding the reservoir wettability is very important for managing well performance, productivity and oil recovery.

  9. Anatomy and dimensions of fluvial crevasse-splay deposits: Examples from the Cretaceous Castlegate Sandstone and Neslen Formation, Utah, U.S.A. (United States)

    Burns, C. E.; Mountney, N. P.; Hodgson, D. M.; Colombera, L.


    Crevasse-splay deposits form a volumetrically significant component of many fluvial overbank successions (up to 90% in some successions).Yet the relationships between the morphological form of accumulated splay bodies and their internal facies composition remains poorly documented from ancient successions. This work quantifies lithofacies distributions and dimensions of exhumed crevasse-splay architectural elements in the Campanian Castlegate Sandstone and Neslen Formation, Mesaverde Group, Utah, USA, to develop a depositional model. Fluvial crevasse-splay bodies thin from 2.1 m (average) to 0.8 m (average) and fine from a coarsest recorded grain size of lower-fine sand to fine silt away from major trunk channel bodies. Internally, the preserved deposits of splays comprise laterally and vertically variable sandstone and siltstone facies associations: proximal parts are dominated by sharp and erosional-based sandstone-prone units, which may be structureless or may comprise primary current lineation on beds and erosional gutter casts; medial parts comprise sets of climbing-ripple strata and small scale deformed beds; distal parts comprise sets of lower-stage plane beds and complex styles of lateral grading into fine-grained floodbasin siltstones and coals. Lithofacies arrangements are used to establish the following: (i) recognition criteria for crevasse-splay elements; (ii) criteria for the differentiation between distal parts of crevasse-splay bodies and floodplain fines; and (iii) empirical relationships with which to establish the extent (ca. 500 m long by 1000 m wide) and overall semi-elliptical planform shape of crevasse-splay bodies. These relationships have been established by high-resolution stratigraphic correlation and palaeocurrent analysis to identify outcrop orientation with respect to splay orientation. This permits lateral changes in crevasse-splay facies architecture to be resolved. Facies models describing the sedimentology and architecture of

  10. Comparison of hydrocarbon gases (C{sub 1}-C{sub 5}) production from Carboniferous Donets (Ukraine) and Cretaceous Sabinas (Mexico) coals

    Energy Technology Data Exchange (ETDEWEB)

    Alsaab, D.; Elie, M.; Izart, A.; Martinez, L. [G2R, Nancy - Universite, CNRS, CREGU, BP-239, 54506 Vandoeuvres-les-Nancy (France); Sachsenhofer, R.F. [Institut fuer Geowissenschaften, Montanuniversitaet Leoben, Peter-Tunner-Strasse 5, A-8700 Leoben (Austria); Privalov, V.A. [Donetsk National Technical University, Artem str., 58, UA-83000 Donetsk (Ukraine); Suarez-Ruiz, I. [Instituto Nacional del Carbon - (INCAR) - CSIC. Ap.Co., 73, 33080-Oviedo (Spain)


    The main purpose of this contribution is to compare the ability of Carboniferous coals from the Donets Basin of the Ukraine and Cretaceous coal from the Sabinas Basin of the Mexico to generate hydrocarbon gases (C{sub 1}-C{sub 5}). Two bituminous coals from the Donets Basin (2c10YD and 1l1Dim; 0.55 and 0.65%R{sub r} respectively) and one bituminous coal from the Sabinas Basin (Olmos, 0.92%R{sub r}) were studied using heating experiments in a confined-pyrolysis system. The highest rank reached during the heating experiments corresponds to the anthracite stage (2.78 and 2.57%R{sub r}) for the 2c10YD and 1l1Dim coals and (2.65%R{sub r}) for the Olmos coal. The composition of the generated (C{sub 1}-C{sub 5}) gases was evaluated using a thermodesorption-multidimensional gas chromatography. The results show that the Carboniferous Donets coals produced more wet gas and methane during pyrolysis than the Cretaceous Olmos coal. This is probably due to their higher liptinite (6-20%) and collodetrinite content and to the loss of a major part of the petroleum potential of the Olmos coal during natural coalification. C{sub 2}-C{sub 5} compounds are mainly derived from the cracking of liquid hydrocarbons. Ethane is the most stable compound and formed from the cracking of higher hydrocarbon component. Large amounts of methane (up to 81 mg/g coal for the Donets coals and 50 mg/g coal for the Sabinas coal) were formed at high temperatures by cracking of previously formed heavier hydrocarbons and by dealkylation of the coal matrix. A linear relationship was observed between methane generation and the maturity level of both coal types. (author)

  11. Nonassociated gas resources in low-permeability sandstone reservoirs, lower tertiary Wasatch Formation, and upper Cretaceous Mesaverde Group, Uinta Basin, Utah

    Energy Technology Data Exchange (ETDEWEB)

    Fouch, T.D.; Schmoker, J.W.; Boone, L.E.; Wandrey, C.J.; Crovelli, R.A.; Butler, W.C.


    The US Geological Survey recognizes six major plays for nonassociated gas in Tertiary and Upper Cretaceous low-permeability strata of the Uinta Basin, Utah. For purposes of this study, plays without gas/water contacts are separated from those with such contacts. Continuous-saturation accumulations are essentially single fields, so large in areal extent and so heterogeneous that their development cannot be properly modeled as field growth. Fields developed in gas-saturated plays are not restricted to structural or stratigraphic traps and they are developed in any structural position where permeability conduits occur such as that provided by natural open fractures. Other fields in the basin have gas/water contacts and the rocks are water-bearing away from structural culmination`s. The plays can be assigned to two groups. Group 1 plays are those in which gas/water contacts are rare to absent and the strata are gas saturated. Group 2 plays contain reservoirs in which both gas-saturated strata and rocks with gas/water contacts seem to coexist. Most units in the basin that have received a Federal Energy Regulatory Commission (FERC) designation as tight are in the main producing areas and are within Group 1 plays. Some rocks in Group 2 plays may not meet FERC requirements as tight reservoirs. However, we suggest that in the Uinta Basin that the extent of low-permeability rocks, and therefore resources, extends well beyond the limits of current FERC designated boundaries for tight reservoirs. Potential additions to gas reserves from gas-saturated tight reservoirs in the Tertiary Wasatch Formation and Cretaceous Mesaverde Group in the Uinta Basin, Utah is 10 TCF. If the potential additions to reserves in strata in which both gas-saturated and free water-bearing rocks exist are added to those of Group 1 plays, the volume is 13 TCF.

  12. Chemical effects of carbon dioxide sequestration in the Upper Morrow Sandstone in the Farnsworth, Texas, hydrocarbon unit

    Energy Technology Data Exchange (ETDEWEB)

    Ahmmed, Bulbul; Appold, Martin S.; Fan, Tianguang; McPherson, Brian J. O. L.; Grigg, Reid B.; White, Mark D.


    Numerical geochemical modeling was used to study the effects on pore-water composition and mineralogy from carbon dioxide (CO2) injection into the Pennsylvanian Morrow B Sandstone in the Farnsworth Unit in northern Texas to evaluate its potential for long-term CO2 sequestration. Speciation modeling showed the present Morrow B formation water to be supersaturated with respect to an assemblage of zeolite, clay, carbonate, mica, and aluminum hydroxide minerals and quartz. The principal accessory minerals in the Morrow B, feldspars and chlorite, were predicted to dissolve. A reaction-path model in which CO2 was progressively added up to its solubility limit into the Morrow B formation water showed a decrease in pH from its initial value of 7 to approximately 4.1 to 4.2, accompanied by the precipitation of small amounts of quartz, diaspore, and witherite. As the resultant CO2-charged fluid reacted with more of the Morrow B mineral matrix, the model predicted a rise in pH, reaching a maximum of 5.1 to 5.2 at a water–rock ratio of 10:1. At a higher water–rock ratio of 100:1, the pH rose to only 4.6 to 4.7. Diaspore, quartz, and nontronite precipitated consistently regardless of the water–rock ratio, but the carbonate minerals siderite, witherite, dolomite, and calcite precipitated at higher pH values only. As a result, CO2 sequestration by mineral trapping was predicted to be important only at low water–rock ratios, accounting for a maximum of 2% of the added CO2 at the lowest water–rock ratio investigated of 10:1, which corresponds to a small porosity increase of approximately 0.14% to 0.15%.

  13. The influence of diagenesis on the reservoir quality of Cambrian and Carboniferous sandstones, southwest Sinai, Egypt (United States)

    McBride, Earle F.; Abdel-Wahab, Antar; Salem, Alaa M. K.


    The diagenetic influence on hydrocarbon reservoir quality was investigated for the Cambrian and Lower Carboniferous sandstones of southwestern Sinai. These quartzose and feldspathic Palaeozoic sandstones were not buried more than 1 to 1.5 km until Late Cretaceous and more recent times, when the most deeply buried rocks may have reached 25 km. Porosity was reduced by compaction from an assumed original 45% to about 26%. In general, both Cambrian and Carboniferous sandstones lost more porosity by compaction (average of 19% for each) than by cementation (average of 17% and 13%, respectively). There is no significant difference in the degree of compaction shown by Cambrian (older, deeper buried) rather than Carboniferous sandstones. Cementation by iron oxide, quartz, calcite and kaolinite reduced porosity to 12-15%, except in silcretes and some ferricretes where porosity was reduced to <5%. Significant secondary porosity was created (5.8 and 5.1 % for Cambrian and Carboniferous sandstones, respectively ) chiefly by dissolution of feldspar. Kaolinite (maximum of 20%) is the most deleterious cement because it has high microporosity, which causes high residual water saturation, and occurs as tiny crystals that have the potential to break loose during rapid fluid flow and block the pore throats. The present-day porosity in these sandstones averages 19% and ranges from 1.5 to 32%. Many sandstone samples (47% of a total of 178 samples) have permeability values higher than 1000 md. The plot of porosity versus the log of permeability has a good correlation indicating that microporosity, even though locally important, does not significantly influence reservoir quality. In spite of their age and the large volumes of groundwater that probably passed through them, these Palaeozoic sandstones retain sufficient porosity and permeability to possess excellent reservoir quality.

  14. An integrated workflow to assess the remaining potential of mature hydrocarbon basins: a case study from Northwest Germany (Upper Jurassic/Lower Cretaceous, Lower Saxony Basin) (United States)

    Seyfang, Björn; Aigner, Thomas; Munsterman, Dirk K.; Irmen, Anton


    Mature hydrocarbon provinces require a high level of geological understanding in order to extend the lives of producing fields, to replace reserves through smaller targets and to reduce the risks of exploring for more and more subtle hydrocarbon traps. Despite a large number of existing wells in the area studied in this paper, the depositional environments and the stratigraphic architecture were still poorly known. In order to improve the geological understanding, we propose a workflow to assess the remaining reservoir potential of mature hydrocarbon areas, integrating cores, cuttings, well-logs, biostratigraphy and seismic data. This workflow was developed for and is exemplified with the northwest of the Lower Saxony Basin (LSB), a mature hydrocarbon province in northwest Germany, but can be applied in a similar fashion to other areas. Systematic integration of lithofacies analysis, chrono- and sequence stratigraphy, combined with electrofacies analysis and modern digital methods like neural network-based lithology determination and 3D facies modelling provides a high-resolution understanding of the spatial facies and reservoir architecture in the study area. Despite widely correlatable litho-units in the Upper Jurassic and Lower Cretaceous in the LSB, complex heterogeneous sedimentary systems can be found in the basin's marginal parts. Two new play types were determined in the study area, showing a remaining potential for stratigraphic hydrocarbon traps. The results of this exploration scale study also provide the basis for re-evaluations on a field development scale. On a basin scale, this study may encourage further data acquisition and re-evaluations to discover previously unknown reservoirs.

  15. An integrated workflow to assess the remaining potential of mature hydrocarbon basins: a case study from Northwest Germany (Upper Jurassic/Lower Cretaceous, Lower Saxony Basin) (United States)

    Seyfang, Björn; Aigner, Thomas; Munsterman, Dirk K.; Irmen, Anton


    Mature hydrocarbon provinces require a high level of geological understanding in order to extend the lives of producing fields, to replace reserves through smaller targets and to reduce the risks of exploring for more and more subtle hydrocarbon traps. Despite a large number of existing wells in the area studied in this paper, the depositional environments and the stratigraphic architecture were still poorly known. In order to improve the geological understanding, we propose a workflow to assess the remaining reservoir potential of mature hydrocarbon areas, integrating cores, cuttings, well-logs, biostratigraphy and seismic data. This workflow was developed for and is exemplified with the northwest of the Lower Saxony Basin (LSB), a mature hydrocarbon province in northwest Germany, but can be applied in a similar fashion to other areas. Systematic integration of lithofacies analysis, chrono- and sequence stratigraphy, combined with electrofacies analysis and modern digital methods like neural network-based lithology determination and 3D facies modelling provides a high-resolution understanding of the spatial facies and reservoir architecture in the study area. Despite widely correlatable litho-units in the Upper Jurassic and Lower Cretaceous in the LSB, complex heterogeneous sedimentary systems can be found in the basin's marginal parts. Two new play types were determined in the study area, showing a remaining potential for stratigraphic hydrocarbon traps. The results of this exploration scale study also provide the basis for re-evaluations on a field development scale. On a basin scale, this study may encourage further data acquisition and re-evaluations to discover previously unknown reservoirs.

  16. A geological overview of the Panuke field reservoir sandstones, offshore Nova Scotia

    Energy Technology Data Exchange (ETDEWEB)

    Hogg, J.R.; DeLong, I.D. [PanCanadian Petroleum Ltd., Calgary, AB (Canada)


    The Panuke oil field, discovered in 1986, was one of the first producing fields in the Canadian offshore with first oil in 1992. The field is associated with the Scotian Basin, an early Cretaceous reservoir with porosity ranging from 20 to 26 per cent and permeability from 500 to 2000 md. The Cohasset and Panuke fields combined, produce an average of 4500 m{sup 3}/d of high gravity oil with a gas-oil ratio of 17 m{sup 3}/m{sup 3}. Migration of the hydrocarbons into the structure is believed to be through a listric normal fault formed by differential subsidence of the Cretaceous sediments over the Jurassic bank edge. Details of the sedimentology and the stratigraphic relationship of the reservoir sandstones of the Panuke field are provided. 4 figs.

  17. Hydrocarbon potential of Early Cretaceous lacustrine sediments from Bima Formation, Yola Sub-basin, Northern Benue Trough, NE Nigeria: Insight from organic geochemistry and petrology (United States)

    Sarki Yandoka, Babangida M.; Abdullah, Wan Hasiah; Abubakar, M. B.; Adegoke, Adebanji Kayode; Maigari, A. S.; Haruna, A. I.; Yaro, Usman Y.


    The Early Cretaceous lacustrine sediments from Bima Formation in the Yola Sub-basin, Northern Benue Trough, northeastern Nigeria were studied based on organic geochemistry and petrology. This is in other to provide information on hydrocarbon generation potential; organic matter type (quality), richness (quantity), origin/source inputs, redox conditions (preservation) and thermal maturation in relation to thermal effect of Tertiary volcanics. The total organic carbon (TOC) contents ranges from 0.38 to 0.86 wt % with extractable organic matter (EOM) below 1000 ppm and pyrolysis S2 yield values from 0.16 to 0.68 mg/g, suggesting poor to fair source rock richness. Based on kerogen pyrolysis and microscopy coupled with biomarker parameters, the organic matters contain Type I (lacustrine algae), Type III (terrestrially derived land-plants) and Type IV kerogens deposited in a mixed lacustrine-terrestrial environment under suboxic to relatively anoxic conditions. This suggest potential occurrence of Early Cretaceous lacustrine sediments (perhaps Lower Cretaceous petroleum system) in Yola Sub-basin of the Northern Benue Trough as present in the neighbouring basins of Chad, Niger and Sudan Republics that have both oil and gas generation potential within the same rift trend (WCARS). Vitrinite reflectance (%Ro) and Tmax values of the lacustrine shales ranges from 1.12 to 2.32 VRo% and 448-501 °C, respectively, indicating peak-late to post-maturity stage. This is supported by the presence of dark brown palynomorphs, amorphous organic matter and phytoclasts as well as inertinite macerals. Consequently, the organic matters in the lacustrine shales of Bima Formation in the Yola Sub-basin appeared as a source of oil (most likely even waxy) and gas prone at a relatively deeper part of the basin. However, the high thermal maturity enhanced the organic matters and most of the hydrocarbons that formed in the course of thermal maturation were likely expelled to the reservoir rock units


    Energy Technology Data Exchange (ETDEWEB)

    David A. Lopez


    Evaluation of the Lower Cretaceous Greybull Sandstone on the Crow Indian Reservation for potential stratigraphic traps in the valley-fill sandstone was the focus of this project. The Crow Reservation area, located in south-central Montana, is part of the Rocky Mountain Foreland structural province, which is characterized by Laramide uplifts and intervening structural basins. The Pryor and Bighorn mountains, like other foreland uplifts, are characterized by asymmetrical folds associated with basement-involved reverse faults. The reservation area east of the mountains is on the northwestern flank of the Powder River Basin. Therefore, regional dips are eastward and southeastward; however, several prominent structural features interrupt these regional dips. The nearly 4,000 mi{sup 2} reservation is under explored but has strong potential for increased oil and gas development. Oil and gas production is well established in the Powder River Basin of Wyoming to the south as well as in the areas north and west of the reservation. However, only limited petroleum production has been established within the reservation. Geologic relations and trends indicate strong potential for oil and gas accumulations, but drilling has been insufficient for their discovery. The Greybull Sandstone, which is part of the transgressive systems tract that includes the overlying Fall River Sandstone, was deposited on a major regional unconformity. The erosional surface at the base of the Greybull Sandstone is the +100 Ma, late Aptian-Early Albian regional unconformity of Weimer (1984). This lowstand erosional surface was controlled by a basin-wide drop in sea level. In areas where incised Greybull channels are absent, the lowstand erosional unconformity is at the base of the Fall River Sandstone and equivalent formations. During the pre-Greybull lowstand, sediment bypassed this region. In the subsequent marine transgression, streams began to aggrade and deposit sand of the lower Greybull Sandstone

  19. Estudio composicional de sedimentitas silicoclasticas y paleosuelos de la formación Mercedes (Cretácico Superior, Uruguay Compositional study of siliciclastics sandstones and paleosoils from the Mercedes Formation (Upper Cretaceous, Uruguay.

    Directory of Open Access Journals (Sweden)

    Ofelia R. Tófalo


    framework, the paleoclimatic fluctuations and the diagenetic processes affecting this unit during the Upper Cretaceous. The Mercedes Formation is located to the west and south of Uruguay, in the Parana Basin. The combined provenance analyses on conglomerates and sandstones show two different source areas with a transitional boundary between them. Towards the north, the volcanic clasts from the underlaying Arapey Formation predominate while there is a minor input from the sandstones of the Guichón Formation and from metamorphic and plutonic sources (Precambriam basement. Besides, in the central-south area the Precambrian clasts are dominant, and fragments from the Arapey Formation are scarce, while here, the Guichón Formation is not a source unit. The sandstone petrography shows interior to continental transitional cratonic provenance. Stable grains are more abundant than metastables and instables suggesting that the sediments where deposited under warm and humid climates. The increase of metaestables altered clasts in the central-south, suggests a near source area. The diagenetic processes were not uniform resulting in a varible porosity distribution, with a predominance of secondary porosity due to dissolution. The recognized processes are clay and iron oxides illuviation, clay neoformation and recristalization, carbonate and silica precipitation and disolution. The uppermost section of this unit has paleosoils, related to the complete infilling of the basin and tectonic quiescence, that suggest a change in the climate, the presence of palygorskyte and illuvial clays imply a semiarid seasonal climate.


    Institute of Scientific and Technical Information of China (English)

    张鹏辉; 张金亮; 董紫睿; 李德勇; 任伟伟; 罗忠琴


    Upper Cretaceous sandstones in the middle of Changling Depression of Songliao Basin mainly belong to lithic arkose, which experienced mechanical compaction,carbonate cementation, clay mineral cementation, silicate cementation, silicic cementation, dissolution of unstable components and local metasomatism. A variety of pore types in studied region include intergranular pores,intragranular pores,moldic pores,as well as a negligible amount of micro-pores and oversized pores. Among the pores,the intergranular pores are dominant. Two stages of oil inclusions in the Hua 5 (the first Member of Nenjiang Formation) were recognized. Hydrocarbon injection of the first period has low maturity,while the second B period possesses little hydrocarbon injection. Based on the diagenetic events, the diagenetic stages of the studied area are diversified from the early eodiagenesis B to the mesodiagenesis B,with the principal diagenetic stage being the mesodi-agenesis A. The classification of diagenetic facies in the area is discussed on the basis of sedimentary facies and diagenesis. Diagenetic facies can be classified into five types: they are compaction diagenetic facies, carbonate-cementation facies, unstable components dissolution facies, siliceous cementation facies and albite diagenetic facies. The unstable components dissolution facies and al-bite diagenetic facies constitute the favorable diagenetic facies in the studied region.%松辽盆地长岭凹陷中部上白垩统储层砂岩主要类型为岩屑长石砂岩,经历的成岩作用主要有以机械压实为主的压实作用,碳酸盐、粘土矿物、硅酸盐及硅质胶结为主的胶结作用,以长石、岩屑等不稳定组分溶解为主的溶蚀作用和局部发育的交代作用.研究区储层孔隙类型以粒间孔隙、粒内溶孔和铸模孔为主,其中粒间孔隙最为发育.储层砂岩成岩演化阶段处于早成岩B期—中成岩B期,主要为中成岩A期.结合沉积相和成岩作用特征,

  1. Sandstone petrofacies in the northwestern sector of the Iberian Basin


    Arribas, J.; Ochoa, M; R Mas; Arribas, Mª E.; González-Acebrón, L.


    [EN] During the most active rifting stages in the northwestern sector of the Iberian Basin (Cameros Basin and Aragonese Branch of the Iberian Range), thick sequences of continental clastic deposits were generated. Sandstone records from Rift cycle 1 (Permo-Triassic) and Rift cycle 2 (Late Jurassic-Early Cretaceous) show similarities in composition. Based on the most recent data, this paper describes sandstone petrofacies developed during both rifting periods. Six petrofacies can be d...

  2. Sandstone petrofacies in the northwestern sector of the Iberian Basin


    Arribas Mocoroa, José; Ochoa, M; Mas Mayoral, José Ramón; Arribas Mocoroa, María Eugenia; González-Acebrón, L.


    During the most active rifting stages in the northwestern sector of the Iberian Basin (Cameros Basin and Aragonese Branch of the Iberian Range), thick sequences of continental clastic deposits were generated. Sandstone records from Rift cycle 1 (Permo-Triassic) and Rift cycle 2 (Late Jurassic-Early Cretaceous) show similarities in composition. Based on the most recent data, this paper describes sandstone petrofacies developed during both rifting periods. Six petrofacies can be distinguishe...

  3. Effect of Hydrocarbon Emplacement on Diagenesis of Silurian Sandstone of Centr al Tarim Basin%塔中地区志留系烃类侵位对成岩作用的影响

    Institute of Scientific and Technical Information of China (English)

    蔡春芳; 顾家裕; 蔡洪美


    Silurian bitumen-bearing sandstones in Central Tarim are shown to be a good ca se to study influence of hydrocarbone mplacement on diagenesis. We have carried it out by means of observation of thi n sections, SEM of sandstones in congwnction with analysis of water chemistry, organic acid anions and δD,δ18O,87Sr/86Sr of oilfield water and homogenization tem peratures of fluid inclusions of the sandstones.   It can be found that quartz secondary overgrowth coexists with reservoir bitumen. Bitumen may occur between quartz overgrowth and grains in coarser san dstones or occlude in the centre of pore in finer sandstones. Homogenization temperatures of organic inclusions are divided into 2 groups: 59.5~82℃ and 103~125℃, sugge stive of at least 2 phases of oil emplacement. The latter is close to the present temperatures of the bore hole bottom, indicating that the late oil and gas empla cement took place in the late Yanshan to early Himalaya Orogeny and quartz overg rowth is not inhibited by oil emplacement,and cementation continueds to present day.   Relationships between Br and Ca, Mg, Sr, Cl, CF(CF=Ca+Mg+Sr-SO4-HCO3,meq/L) sho w that oilfield water is evolved by subaerial evaporation of seawater and subseq uent mixing with meteoric water evidenced by relationship between δD and δ 18O . Relative enrichment of Ca, Sr, K and depletion of Mg is explained to be a resu lt of dissolution of K-feldspar,dolomitization of calcite and albitiyation of feldspar.87Sr/86Sr of 14 water samples range from 0 .710 44 to 0.712 58 ,much larger tha n Silurian seawater, indicating that Rb-enriched detrital minerals such as K-f el dspar, mica and illite from sandstone or mudstone contribute significant amount of 87Sr to oilfield waters.   It is proposed that organic acids and anions,hydrocarbons be generated by as a result of meteoric water influx after oil emplacement. Organic acids en hance dissolution of minerals such as K-feldspar, quartz, leading to

  4. Sedimentary basin analysis and petroleum potential of the Cretaceous and Tertiary strata in Korea.

    Energy Technology Data Exchange (ETDEWEB)

    Son, Jin-Dam; Kwak, Young-Hoon; Bong, Pil-Yoon [Korea Institute of Geology Mining and Materials, Taejon (KR)] (and others)


    Since 1992 sedimentary basin analysis to assess petroleum potential of the Cretaceous and Tertiary strata in the Korean onshore and continental shelf have been carried out. The Cretaceous non-marine strata mainly occupy the Gyeongsang Basin in southeastern part of the Korean Peninsula and small basins such as Haenam and Gyeokpo depressions in western coastal areas. The Tertiary strata are mostly distributed in Domi, Cheju, Socotra subbasins, and Okinawa Trough in the South Continental Shelf, and Kunsan and Heuksan basins in the West. The basin evolution and petroleum potential for each basins are characterized as follow. The Cretaceous Gyeongsang sediments were deposited in three subbasins including Milyang, Euisung and Yongyang subbasins. The black shales in Nakdong and Jinju formations are interpreted to contain abundant organic matter during the deposition, thermal maturity reaching up to the zone of dry gas formation. Because porosity and permeability are too low, the sandstones can act as a tight gas reservoir rather than conventional oil and gas reservoir. The latest Cretaceous strata of Haenam and Kyeokpo depressions in western coastal area are correlated into the Yuchon Volcanic Group of the Gyeongsang Basin. Petroleum potential of the Early Cretaceous basin in the West Continental Shelf could be relatively high in terms of sedimentary basin filled with thick lacustrine sediments. The Kunsan basin in the West Continental Shelf originated in the Early Cretaceous time expanded during the Paleocene time followed by regional erosion at the end of Paleocene on which Neogene sediment have been accumulated. The Paleocene-Eocene sublacustrine shales may play an major role as a source and cap rocks. South Continental Shelf Basin is subdivided by Cheju subbasin in the center, Socotra Subbasin to the west, Domi Subbasin to the northeast and Okinawa Trough to the East. The potential hydrocarbon traps associated with anticline, titled fault blocks, fault, unconformity

  5. Sequence Stratigraphic Analysis and Facies Architecture of the Cretaceous Mancos Shale on and Near the Jicarilla Apache Indian Reservation, New Mexico-their relation to Sites of Oil Accumulation

    Energy Technology Data Exchange (ETDEWEB)

    Ridgley, Jennie


    The purpose of phase 1 and phase 2 of the Department of Energy funded project Analysis of oil- bearing Cretaceous Sandstone Hydrocarbon Reservoirs, exclusive of the Dakota Sandstone, on the Jicarilla Apache Indian Reservation, New Mexico was to define the facies of the oil producing units within the Mancos Shale and interpret the depositional environments of these facies within a sequence stratigraphic context. The focus of this report will center on (1) redefinition of the area and vertical extent of the ''Gallup sandstone'' or El Vado Sandstone Member of the Mancos Shale, (2) determination of the facies distribution within the ''Gallup sandstone'' and other oil-producing sandstones within the lower Mancos, placing these facies within the overall depositional history of the San Juan Basin, (3) application of the principals of sequence stratigraphy to the depositional units that comprise the Mancos Shale, and (4) evaluation of the structural features on the Reservation as they may control sites of oil accumulation.

  6. Continuity and internal properties of Gulf Coast sandstones and their implications for geopressured fluid production

    Energy Technology Data Exchange (ETDEWEB)

    Morton, R.A.; Ewing, T.E.; Tyler, N.


    The intrinsic properties of the genetic sandstone units that typify many geopressured geothermal aquifers and hydrocarbon reservoirs in the Gulf Coast region were systematically investigated classified, and differentiated. The following topics are coverd: structural and stratigraphic limits of sandstone reservoirs, characteristics and dimensions of Gulf Coast sandstones; fault-compartment areas; comparison of production and geologic estimates of aquifer fluid volume; geologic setting and reservoir characteristics, Wells of Opportunity; internal properties of sandstones; and implications for geopressured fluid production. (MHR)

  7. Solid hydrocarbon: a migration-of-fines problem in carbonate reservoirs

    Energy Technology Data Exchange (ETDEWEB)

    Lomando, A.J.


    The most familiar example of a migration-of-fines problem is authigenic kaolinite, which can detach, migrate through a pore system, and bridge pore throats, thus reducing permeability. under certain conditions, a similar problem is caused by solid hydrocarbon, independent of a mode of origin, which has precipitated in carbonate pore systems. Cores from several reservoirs in the Lower Cretaceous of east Texas were used as the data base in this study. Three morphotypes of solid hydrocarbon have been identified from thin-section and scanning electron microscope observations: droplets, peanut brittle, and carpets. Droplets are small, individual, rounded particles scattered on pore walls. Peanut brittle ranges from a continuous to discontinuous thin coating with random rounded lumps that probably have droplet precursors. Carpets are thick, continuous coatings and, at the extreme, can effectively occlude whole pores. Initially, solid hydrocarbon reduces permeability without necessarily decreasing porosity significantly. Likewise, solid hydrocarbon cannot be detected directly from wireline logs. Acidizing to enhance communication to the well bore is a common completion procedure in limestone and calcareous sandstone reservoirs. In reservoirs containing solid hydrocarbon, acid etches the substrate and releases solid hydrocarbon, which migrates in the pore system and bridges pore throats. Differential well-bore pressure also may cause solid hydrocarbon to migrate. Therefore, wettability, which controls hydrocarbon adhesion to the pore walls, and the dominant morphotype are important factors in the extent of reservoir damage.

  8. 塔南凹陷早白垩世构造演化及其对沉积充填和砂体分布的控制%Controls of the Lower Cretaceous structures on the sedimentary filling and sandstone distribution in southern Tanan depression

    Institute of Scientific and Technical Information of China (English)

    许凤鸣; 张晓东; 王涛


    塔南凹陷早白垩世经历了断陷初期冲积-滨浅湖盆层序、强烈断陷期半深湖-深湖湖盆层序及断坳期三角洲-湖泊盆型层序的沉积演化序列.受盆地整体格架的控制,凹陷内可划分出5个次级构造单元,各次级构造单元古构造格架决定了沉积相带展布、砂体的发育和分布.%Under the controls of tectonic evolution of the Tamuchage Basin, the Tanan depression went through three sedimentary evolutionary sequences during the Early Cretaceous, including the alluvial to littoral-shallow lake basin sequences during the early stage of rift faulting, bathyal-abyssal lake basin sequences during the climax of rift faulting, and delta-lake basin sequences during the fault depression stage. Five secondary tectonic units have been distinguished for the Tanan depression, including eastern steep slope zone, eastern secondary depression, central low uplift, western secondary depression and western ramp zone. The tectonic framework mentioned above has exercised a major control on the distribution of sedimentary facies and sandstone bodies.

  9. Synkinematic quartz cementation in partially open fractures in sandstones (United States)

    Ukar, Estibalitz; Laubach, Stephen E.; Fall, Andras; Eichhubl, Peter


    Faults and networks of naturally open fractures can provide open conduits for fluid flow, and may play a significant role in hydrocarbon recovery, hydrogeology, and CO2 sequestration. However, sandstone fracture systems are commonly infilled, at least to some degree, by quartz cement, which can stiffen and occlude fractures. Such cement deposits can systematically reduce the overall permeability enhancement due to open fractures (by reducing open fracture length) and result in permeability anisotropies. Thus, it is important to identify the factors that control the precipitation of quartz in fractures in order to identify potential fluid conduits under the present-day stress field. In many sandstones, quartz nucleates syntaxially on quartz grain or cement substrate of the fracture wall, and extends between fracture walls only locally, forming pillars or bridges. Scanning electron microscope cathodoluminescence (SEM-CL) images reveal that the core of these bridges are made up of bands of broken and resealed cement containing wall-parallel fluid inclusion planes. The fluid inclusion-rich core is usually surrounded by a layer of inclusion-poor clear quartz that comprises the lateral cement. Such crack-seal textures indicate that this phase was precipitating while the fractures were actively opening (synkinematic growth). Rapid quartz accumulation is generally believed to require temperatures of 80°C or more. Fluid inclusion thermometry and Raman spectroscopy of two-phase aqueous fluid-inclusions trapped in crack-seal bands may be used to track the P-T-X evolution of pore fluids during fracture opening and crack-seal cementation of quartz. Quartz cement bridges across opening mode fractures in the Cretaceous Travis Peak Formation of the tectonically quiescent East Texas Basin indicate individual fractures opened over a 48 m.y. time span at rates of 16-23 µm/m.y. Similarly, the Upper Cretaceous Mesaverde Group in the Piceance Basin, Colorado contains fractures that

  10. Greybull Sandstone Petroleum Potential on the Crow Indian Reservation, South-Central Montana

    Energy Technology Data Exchange (ETDEWEB)

    Lopez, David A.


    The focus of this project was to explore for stratigraphic traps that may be present in valley-fill sandstone at the top of the Lower Cretaceous Kootenai Formation. This sandstone interval, generally known as the Greybull Sandstone, has been identified along the western edge of the reservation and is a known oil and gas reservoir in the surrounding region. The Greybull Sandstone was chosen as the focus of this research because it is an excellent, well-documented, productive reservoir in adjacent areas, such as Elk Basin; Mosser Dome field, a few miles northwest of the reservation; and several other oil and gas fields in the northern portion of the Bighorn Basin.

  11. Kaolinite Mobilisation in Sandstone

    DEFF Research Database (Denmark)

    Rosenbrand, Esther; Fabricius, Ida Lykke; Kets, Frans


    The effect of temperature and salinity on sandstone permeability is critical to the feasibility of heat storage in geothermal aquifers. Permeability reduction has been observed in Berea sandstone when the salinity of the pore water is reduced as well as when the sample is heated. Several authors...

  12. Incised valley filling deposits: an important pathway system for long-distance hydrocarbon migration——a case study of the Fulaerji Oilfield in the Songliao Basin

    Institute of Scientific and Technical Information of China (English)

    Xin Renchen; Liu Hao; Li Guifan


    In this paper, incised valley filling deposits, which formed an important pathway system for long-distance hydrocarbon migration, are discussed in detail based on core and logging data. The sequence SQy23 of the Cretaceous Yaojia Formation is the main hydrocarbon-beating layer in the Fulaerji Oilfield. The hydrocarbon source of the oilfield is the Qijia-Gulong Sag which is about 80 km away from the Fulaerji Oilfield. The transport layer of long-distance hydrocarbon migration is the overlapped sandstone complex which fills the incised valley. The incised valley developed during the depositional period from the late Qingshankou Formation to the early Yaojia Formation of Cretaceous (SQqn4-SQy1)was about 70 km long and 20 km wide, and extended in the NW-SE direction. The overlapped filling of the incised valley mainly occurred in the expanding system tract of the third-order sequence SQy23 (ESTy23). Towards the basin, incised valley filling deposits overlapped on the delta developed in the early period, and towards the basin margin, incised valley filling deposits were covered by the shore-shallow lacustrine sandy beach bar developed in the maximum flooding period. All of the delta, the incised valley filling and the shore-shallow sandy beach bar are sandstone-rich, and have high porosity and permeability, and can form an effective hydrocarbon migration and accumulation system. Deltaic sand bodies collected and pumped hydrocarbon from the active source, incised valley filling depositional system completed the long-distance hydrocarbon migration, and lithological traps of shore-shallow lacustrine sandy beach bar accumulated hydrocarbon. The incised valley filling sequences are multi-cycle: an integrated short- term filling cycle was developed on the erosion surface, and the sequences upward were mud-gravel stone, medium-fine sandstone containing terrigenous gravels and muddy pebbles with cross bedding, silty mudstone with ripple bedding, and mudstone. The incised valley

  13. Two sources and three charging events of hydrocarbons in Lower Cretaceous reservoirs in Shaya uplift, Tarim Basin: evidence from fluid inclusion analysis%塔里木盆地沙雅隆起下白垩统双源三幕油气充注成藏的流体包裹体证据

    Institute of Scientific and Technical Information of China (English)

    斯尚华; 陈红汉; 丰勇; 王月蕾


    Lots of hydrocarbon inclusions and bitumen have been measured in 90 sandstone samples from the Lower Cretaceous of Shaya uplift, Tarim Basin, and the evidence from these measurements can be used to trace the hydrocarbon migration and accumulation history of the basin. Four types of inclusions were determined in fluorescence observation, i. e. gas-liquid biphase oil inclusions, pure gas inclusions, oil-asphalt inclusions and aqueous inclusions. According to fluorescence properties(fluorescent colors, λmax and QF535) of the oil inclusion and combined with the employment of homogenization temperature of aqueous inclusions projected on a burial history diagram, three oil charging events were determined, and they took place in 12-5 Ma, 5-2 Ma and 2-0 Ma, respectively. By the fluorescence spectral comparison of the oil inclusion with the crude oil from oil-prone source beds, it could be concluded that the first and the second charging oils originated from terrigeneous source rocks while the third charging oil was derived from marine ones. The marine oil is characterized by a lower maturity and later charging time compared with the continental oil. Its hydrocarbon accumulation occurred mainly during the middle-late Himalayan period, and is characterized by continuous and rapid charging.%对90块砂岩流体包裹体样品系统分析表明,塔里木盆地沙雅隆起下白垩统存在大量沥青和烃类包裹体,这些证据可以追踪盆地内油气的运移聚集和成藏过程.利用荧光观察确定包裹体类型主要有4种:气液两相油包裹体;纯气相包裹体;油-沥青两相包裹体;盐水包裹体.依据油包裹体荧光性质(荧光颜色、主峰波长和QF535),结合盐水包裹体均一温度-埋藏史投影方法,确定雅沙隆起下白垩统有1期3幕油充注:第1幕12~5 Ma、第2幕5~2 Ma、第3幕2~0Ma;通过油包裹体与油源层原油的荧光光谱对比,判定第1幕和第2幕为陆相油源充注,第3幕为海相

  14. Sedimentology and reservoir heterogeneity of a valley-fill deposit-A field guide to the Dakota Sandstone of the San Rafael Swell, Utah (United States)

    Kirschbaum, Mark A.; Schenk, Christopher J.


    Valley-fill deposits form a significant class of hydrocarbon reservoirs in many basins of the world. Maximizing recovery of fluids from these reservoirs requires an understanding of the scales of fluid-flow heterogeneity present within the valley-fill system. The Upper Cretaceous Dakota Sandstone in the San Rafael Swell, Utah contains well exposed, relatively accessible outcrops that allow a unique view of the external geometry and internal complexity of a set of rocks interpreted to be deposits of an incised valley fill. These units can be traced on outcrop for tens of miles, and individual sandstone bodies are exposed in three dimensions because of modern erosion in side canyons in a semiarid setting and by exhumation of the overlying, easily erodible Mancos Shale. The Dakota consists of two major units: (1) a lower amalgamated sandstone facies dominated by large-scale cross stratification with several individual sandstone bodies ranging in thickness from 8 to 28 feet, ranging in width from 115 to 150 feet, and having lengths as much as 5,000 feet, and (2) an upper facies composed of numerous mud-encased lenticular sandstones, dominated by ripple-scale lamination, in bedsets ranging in thickness from 5 to 12 feet. The lower facies is interpreted to be fluvial, probably of mainly braided stream origin that exhibits multiple incisions amalgamated into a complex sandstone body. The upper facies has lower energy, probably anastomosed channels encased within alluvial and coastal-plain floodplain sediments. The Dakota valley-fill complex has multiple scales of heterogeneity that could affect fluid flow in similar oil and gas subsurface reservoirs. The largest scale heterogeneity is at the formation level, where the valley-fill complex is sealed within overlying and underlying units. Within the valley-fill complex, there are heterogeneities between individual sandstone bodies, and at the smallest scale, internal heterogeneities within the bodies themselves. These

  15. Key Elements Controlling Oil Accumulation within the Tight Sandstones

    Institute of Scientific and Technical Information of China (English)

    Haiyan Hu; Zhiping Zeng; Jianzhang Liu


    Tight oil sandstone reservoirs with low porosity and permeability, which are an uncon-ventional petroleum resource, have been discovered in the Jurassic intervals of the central Junggar Ba-sin, the northwestern China. To reveal the accumulation mechanism, a relatively comprehensive re-search was conducted, including oil-source correlation, porosity evolution, and hydrocarbon charging history. The results show that crude oil of these tight sandstone reservoirs were mainly from Permian source rocks with some contribution from Jurassic source rocks. The reservoirs were buried at shallow depth (5%). In contrast, the sandstone reservoir had already become tight and did not provide available space to ac-cumulate oil due to severe compaction and cementation when hydrocarbon from Jurassic source rock filled, evidenced by low GOI values (<5%). Therefore, reservoir porosity controls the oil accumulation within tight sandstone. Whether tight sandstone reservoirs accumulate oil depends on the reservoir quality when hydrocarbons charge. Before the exploration of tight oil sandstone reservoirs, it should be required to investigate the relationship between oil charging history and porosity evolution to reduce the exploration risk and figure out the available targets.

  16. Distribution characteristics and petroleum geological significance of the Silurian asphaltic sandstones in Tarim Basin

    Institute of Scientific and Technical Information of China (English)

    ZHANG; Jun; PANG; Xiongqi; LIU; Luofu; JIANG; Zhenxue; LIU


    The Tarim Basin is a typical superimposed basin in which there have occurred multiphase adjustment and destruction of the reservoirs. The widely distributed asphaltic sandstones of the Silurian are the very product after destruction of the reservoirs. Studies show that the Silurian asphaltic sandstones distributed in both the middle and western parts on the basin are controlled chiefly by the Caledonian oil source area and by the Tazhong, Tabei and Bachu uplifts, whereas the distribution of the asphaltic sandstones on local structural belts is controlled by the reservoir's sedimentary system. Vertically, most of the asphaltic sandstones are under the regional caprock of red mudstones and the upper sandstone section of compact lithology. Due to the difference of hydrocarbon destruction in the early stage and the influence of hydrocarbon recharge in the late stage, the asphaltic sandstones and oil-bearing sandstones in the Tazhong area can be vertically divided into the upper and lower sections and they have an interactive distribution relationship as well. Asphaltic sandstones exist not only in intergranular pores but also inside the grains of sand and between the crevices, proving the destruction of early reservoirs due to uplifting. The existence of asphaltic sandstones over a large area reveals that the large-scale migration and accumulation and the subsequent destruction of hydrocarbons in the Craton area. The destruction caused a loss of the reserve resources of the Palaeozoic amounting to nearly 13.3 billion tons. Asphaltic sandstones formed after the destruction of oil and gas may serve as an effective caprock which is beneficial to accumulation of hydrocarbons and formation of the pool sealed by asphaltic sandstones in the later stage. The destruction of the early Silurian hydrocarbons depends on the stratigraphic burial depth. The deep part under the northern slope of Tazhong is an area favorable to search of undestroyed Silurian oil reservoirs.

  17. Stochastic reconstruction of sandstones (United States)

    Manwart; Torquato; Hilfer


    A simulated annealing algorithm is employed to generate a stochastic model for a Berea sandstone and a Fontainebleau sandstone, with each a prescribed two-point probability function, lineal-path function, and "pore size" distribution function, respectively. We find that the temperature decrease of the annealing has to be rather quick to yield isotropic and percolating configurations. A comparison of simple morphological quantities indicates good agreement between the reconstructions and the original sandstones. Also, the mean survival time of a random walker in the pore space is reproduced with good accuracy. However, a more detailed investigation by means of local porosity theory shows that there may be significant differences of the geometrical connectivity between the reconstructed and the experimental samples.

  18. Depositional environments of the subsurface Cretaceous deposits of southeastern North Carolina (United States)

    Custer, E. S., Jr.


    The subsurface Cretaceous deposits of southeastern North Carolina were analyzed. Six lithologic units were recognized. These are, in ascending stratigraphic order: an unnamed Lower Cretaceous unit, Cape Fear Formation, unnamed Upper Cretaceous unit, Middendorf Formation, Black Creek Formation, and Peedee Formation. The unnamed Lower Cretaceous unit contains interbedded fine to medium grained sands, calcareous sandstones, sandy limestones and clays which were deposited in environments ranging from nearshore to fluvial. The Cape Fear Formation consists of very fine to coarse tan sands interbedded with brown and reddish clays. The Upper Cretaceous unnamed unit is composed of tan and yellow medium to coarse sands interbedded with tan and red clays deposited in braided fluvial environments. The Black Creek Formation consists of lignitic dark clays and coarse to very fine sands. Formation is composed of dark green to greenish-gray, micaceous, glauconitic clays and sands interbedded with calcareous sandstones or sandy limestones.

  19. Cretaceous stratigraphy and biostratigraphy, Sierra Blanca basin, southeastern New Mexico

    Energy Technology Data Exchange (ETDEWEB)

    Lucas, S.G. (New Mexico Museum of Natural History, Albuquerque, NM (United States)); Anderson, O.R. (New Mexico Bureau of Mines Mineral Resources, Socorro, NM (United States))


    The Sierra Blanca basin of Otero and Lincoln counties, New Mexico contains a Lower (upper Albian)-Upper (Santonian) Cretaceous section of marine and nonmarine strata as much as 700 m thick which represent the upper part of a regressive cycle followed by two transgressive-regressive deposition cycles. The lower 55 m of the Cretaceous section are the same tripartite Dakota Group units recognized in Guadalupe and San Miguel counties: basal Mesa Rica Sandstone (late Albian), medial Pajarito formation (late Albian) and upper Romeroville sandstone (earliest Cenomanian). The Mesa Rica and Pajarito represent a regression and are overlain disconformably by the transgressive Romeroville sandstone. Overlying transgressive marine clastics and minor carbonates of the Mancos Shale are as much as 73 m thick and include the early Turonian Greenhorn Limestone. The overlying Tres Hermanos formation (up to 91 m thick) consists of the (ascending order) Atarque sandstone and the Carthage and Fite Ranch sandstone members. These strata represent a mid-Turonian regression in response to regional tectonism (Atarque and Carthage), followed by a transgression (Fite Ranch sandstone) that ended in the deposition of the D-Cross Tongue of the Mancos Shale and Fort Hays Member of the Niobrara Formation during the late Turonian. The subsequent regression began with the Coniacian Gallup Sandstone (55 m) followed by coal-bearing Crevasse Canyon Formation (up to 244 m thick). The Coniacian-Santonian Crevasse Canyon Formation, the youngest Cretaceous unit in the basin, is disconformably overlain by middle Eocene conglomerates and red-bed siliciclastics of the Cub Mountain formation. Dakota Group age determinations in the Sierra Blanca basin are those of well-dated sections to the north, but ammonites and inoceramid bivalves from the Sierra Blanca basin provide precise age control for Cenomanian-Santonian marine and marginal marine strata and palynology and megafossil plants for nonmarine strata.

  20. Sequence stratigraphy of the Kingak Shale (Jurassic-Lower Cretaceous), National Petroleum Reserve in Alaska (United States)

    Houseknecht, D.W.; Bird, K.J.


    Beaufortian strata (Jurassic-Lower Cretaceous) in the National Petroleum Reserve in Alaska (NPRA) are a focus of exploration since the 1994 discovery of the nearby Alpine oil field (>400 MMBO). These strata include the Kingak Shale, a succession of depositional sequences influenced by rift opening of the Arctic Ocean Basin. Interpretation of sequence stratigraphy and depositional facies from a regional two-dimensional seismic grid and well data allows the definition of four sequence sets that each displays unique stratal geometries and thickness trends across NPRA. A Lower to Middle Jurassic sequence set includes numerous transgressive-regressive sequences that collectively built a clastic shelf in north-central NPRA. Along the south-facing, lobate shelf margin, condensed shales in transgressive systems tracts downlap and coalesce into a basinal condensed section that is likely an important hydrocarbon source rock. An Oxfordian-Kimmeridgian sequence set, deposited during pulses of uplift on the Barrow arch, includes multiple transgressive-regressive sequences that locally contain well-winnowed, shoreface sandstones at the base of transgressive systems tracts. These shoreface sandstones and overlying shales, deposited during maximum flooding, form stratigraphic traps that are the main objective of exploration in the Alpine play in NPRA. A Valanginian sequence set includes at least two transgressive-regressive sequences that display relatively distal characteristics, suggesting high relative sea level. An important exception is the presence of a basal transgressive systems tract that locally contains shoreface sandstones of reservoir quality. A Hauterivian sequence set includes two transgressive-regressive sequences that constitute a shelf-margin wedge developed as the result of tectonic uplift along the Barrow arch during rift opening of the Arctic Ocean Basin. This sequence set displays stratal geometries suggesting incision and synsedimentary collapse of the shelf

  1. Sedimentology and Reservoir Characteristics of Early Cretaceous Fluvio-Deltaic and Lacustrine Deposits, Upper Abu Gabra Formation, Sufyan Sub-basin, Muglad Rift Basin, Sudan (United States)

    Yassin, Mohamed; Abdullatif, Osman; Hariri, Mustafa


    Sufyan Sub-basin is an East-West trending Sub-basin located in the northwestern part of the Muglad Basin (Sudan), in the eastern extension of the West and Central Africa Rift System (WCARS). The Early Cretaceous Abu Gabra Formation considered as the main source rock in the Muglad Basin. In Sufyan Sub-basin the Early Cretaceous Upper Abu Gabra Formation is the main oil-producing reservoir. It is dominated by sandstone and shales deposited in fluvio-deltaic and lacustrine environment during the first rift cycle in the basin. Depositional and post-depositional processes highly influenced the reservoir quality and architecture. This study investigates different scales of reservoir heterogeneities from macro to micro scale. Subsurface facies analysis was analyzed based on the description of six conventional cores from two wells. Approaches include well log analysis, thin sections and scanning electron microscope (SEM) investigations, grain-size, and X-ray diffraction (XRD) analysis of the Abu Gabra sandstone. The cores and well logs analyses revealed six lithofacies representing fluvio-deltaic and lacustrine depositional environment. The sandstone is medium to coarse-grained, poorly to moderately sorted and sub-angular to subrounded, Sub-feldspathic arenite to quartz arenite. On macro-scale, reservoir quality varies within Abu Gabra reservoir where it shows progressive coarsening upward tendencies with different degrees of connectivity. The upper part of the reservoir showed well connected and amalgamated sandstone bodies, the middle to lower parts, however, have moderate to low sandstone bodies' connectivity and amalgamation. On micro-scale, sandstone reservoir quality is directly affected by textures and diagenesis.The XRD and SEM analyses show that kaolinite and chlorite clay are the common clay minerals in the studied samples. Clay matrix and quartz overgrowth have significantly reduced the reservoir porosity and permeability, while the dissolution of feldspars

  2. Continuity and internal properties of Gulf Coast sandstones and their implications for geopressured energy development. Annual report, November 1, 1980-October 31, 1981

    Energy Technology Data Exchange (ETDEWEB)

    Morton, R.A.; Ewing, T.E.; Tyler, N.


    Systematic investigation, classification, and differentiation of the intrinsic properties of genetic sandstone units that typify many geopressured geothermal aquifers and hydrocarbon reservoirs of the Gulf Coast region are provided. The following are included: structural and stratigraphic limits of sandstone reservoirs; characteristics and dimensions of Gulf Coast Sandstones; fault compartment areas; comparison of production and geologic estimates of aquifer volume; geologic setting and reservoir characteristics, wells of opportunity; internal properties of sandstones and implications for geopressured energy development. (MHR)

  3. U-Pb Ages and Hf Isotope Compositions of Detrital Zircons from the Sandstone in the Early Cretaceous Wawukuang Formation in the Jiaolai Basin, Shandong Province and its Tectonic Implications%胶莱盆地早白垩世瓦屋夼组砂岩中碎屑锆石U-Pb-Hf同位素组成及其构造意义

    Institute of Scientific and Technical Information of China (English)

    霍腾飞; 杨德彬; 许文良; 王枫; 刘海彬; 师江朋


    LA-ICP-MS U-Pb dating and in situ Hf isotope analysis were carried out for the detrital zircons to constrain the depositional age and provenance of the Wawukuang Formation, which is believed as the earliest unit of the Laiyang Group in the Jiaolai Basin, and its implications. Most of these detrital zircons from the feldspar quartz sandstone in the Wawukuang Formation are magmatic in origin, which are euhedral-subhedral and display oscillatory zoning in CL images; whereas few Late Triassic detrital zircons are metamorphic in origin and structureless in CL images. U-Pb isotopic dating of 82 zircon grains yields age populations at ca. 129 Ma, 158 Ma, 224 Ma, 253 Ma, 461 Ma, 724 Ma, 1851 Ma and 2456 Ma. U-Pb dating and Hf isotopic results indicate that:1) the Wawukuang Formation deposited during the Early Cretaceous (129–106 Ma);2) the detrital zircons with the ages of 1851 Ma and 2456 Ma mainly sourced from the Precambrian basement rocks of the North China Craton;the Neoproterozoic (729–721 Ma) magmatic zircons and the Late Triassic (226–216 Ma) metamorphic zircons sourced from the Su-Lu terrane; The Late Paleozoic detrital zircons could source from the Late Paleozoic igneous rocks in the northern margin of the North China Craton;the Late Triassic (231–223 Ma) magmatic zircons and the 158–129 Ma zircons sourced from the coeval igneous rocks in the Jiaobei and Jiaodong;3) the deposition age and provenance of the Jiaolai Basin are different from those of the Hefei Basin; 4) the recognition of clastic sediments from the Su-Lu terrane in the Wawukuang Formation suggests that the Su-Lu terrane was under denudation in the Early Cretaceous.%本文报道了胶莱盆地莱阳群最底部瓦屋夼组长石石英砂岩中碎屑锆石的LA-ICP-MS U-Pb年代学和原位Hf同位素分析结果,进而约束了瓦屋夼组砂岩的沉积时代和物源及其构造意义。碎屑锆石多数呈自形–半自形晶,发育岩浆生长环带,暗示它们为岩浆成因

  4. Evolution of hydrocarbon migration style in a fractured reservoir deduced from fluid inclusion data, Clair Field, west of Shetland, UK

    Energy Technology Data Exchange (ETDEWEB)

    Baron, Martin; Parnell, John; Mark, Darren [Department of Geology and Petroleum Geology, Meston Building, University of Aberdeen, King' s College, Aberdeen AB24 3UE (United Kingdom); Carr, Andrew [Advanced Geochemical Systems Ltd., Towles Fields, Burton on the Wolds, Leicestershire LE12 5TD (United Kingdom); British Geological Survey, Keyworth, Nottingham NG12 5GG (United Kingdom); Przyjalgowski, Milosz [Department of Physics, National University of Ireland-Galway, Galway (Ireland); Feely, Martin [Department of Geology, National University of Ireland-Galway, Galway (Ireland)


    A petrographic and fluid inclusion microthermometric study was performed on sandstones from the Devonian-Carboniferous reservoir rocks of the Clair Field, west of Shetland. Fluid inclusion petrographic and microthermometric observations were collected from quartz, K-feldspar and calcite cements and veins. Vein and cement minerals host both aqueous and hydrocarbon two-phase (liquid and vapor-filled) fluid inclusions indicating that cementation occurred during oil charging. The location of hydrocarbon fluid inclusions in the paragenetic sequence of the reservoir rocks indicates that hydrocarbon migration during early-stage diagenesis occurred via intergranular pores as well as fractures, whereas towards the later stages of diagenesis, as porosities were occluded, hydrocarbon migration was predominantly fracture controlled. The microthermometric characteristics of primary and secondary aqueous fluid inclusions in association with hydrocarbon fluid inclusions indicates that cementation and veining during oil charging occurred at temperatures up to 180 C. Salinity values are variable (0-10.9 wt% NaCl eq.) indicating that fluid mixing occurred during veining and cementation. Basin modeling and vitrinite reflectance data indicate that temperatures of up to 180 C could not have been attained through burial alone. The high temperatures attained during late-stage diagenesis are interpreted to be caused by high temperature, short-lived fluids circulating within the Devonian-Carboniferous reservoir rocks in association with late Cretaceous and Paleocene magmatism. These high temperature fluid flow events were not recorded in the vitrinite reflectance data because of their short duration. (author)

  5. Effective Thermal Conductivity Modeling of Sandstones: SVM Framework Analysis (United States)

    Rostami, Alireza; Masoudi, Mohammad; Ghaderi-Ardakani, Alireza; Arabloo, Milad; Amani, Mahmood


    Among the most significant physical characteristics of porous media, the effective thermal conductivity (ETC) is used for estimating the thermal enhanced oil recovery process efficiency, hydrocarbon reservoir thermal design, and numerical simulation. This paper reports the implementation of an innovative least square support vector machine (LS-SVM) algorithm for the development of enhanced model capable of predicting the ETCs of dry sandstones. By means of several statistical parameters, the validity of the presented model was evaluated. The prediction of the developed model for determining the ETCs of dry sandstones was in excellent agreement with the reported data with a coefficient of determination value ({R}2) of 0.983 and an average absolute relative deviation of 0.35 %. Results from present research show that the proposed LS-SVM model is robust, reliable, and efficient in calculating the ETCs of sandstones.

  6. Lithofacies Architecturing and Hydrocarbon Reservoir Potential of Lumshiwal Formation: Surghar Range, Trans-Indus Ranges, North Pakistan

    Directory of Open Access Journals (Sweden)

    Iftikhar Alam


    Full Text Available Western environs of the Indo-Pak Plate are comprised of thick Mesozoic sedimentary sequence and extensively extended toward Trans-Indus Salt ranges of North Pakistan. This sequence consists of detrital clastic sediments in the lower level and shallow to deep marine sediments in the upper level. In the Trans-Indus Salt ranges the Lumshiwal Formation represents the transitional level of the lower Cretaceous sequence. In Surghar Range the lower part of formation is composed of cyclic alteration of clayey, silty, very fine grained greenish gray, glauconitic sandstone to rusty brownish gray sandstone. The middle part of formation is comprised of thick bedded to massive, cliff forming, sugary texture, whitish to light yellowish gray occasionally rusty brownish gray medium to coarse grained, moderate to well cemented sandstone. The upper part is comprised of feldspathic, ferruginous, weathering yellowish brown, rusty brown to light gray with locally calcareous sandstone beds. The sandstone is reddish to brownish gray, coarse to granules texture, moderately cemented thick bedded to massive. Total thickness of the formation is 220m at Baroch Nala section 230m in Karandi section at a dip of 60°. Along trend lithological variations and diversified primary sedimentary structures which classifies fifteen different sub-lithofacie in Lumshiwal. Middle and upper parts of the formation show massive to thick, current bedded deposits. Lithofacies analysis revealed that the Lumshiwal Formation was deposited in shallow marine for the lower cyclic part to transitionally prodeltaic to deltaic for the middle to upper part respectively. High silica contents in the upper part compare to the middle and lower part of the formation. On the basis of high silica and low alumina with other low fractions of rock fragments, the sandstone is categorized into quartzarenite, sub-litharenite and sub-arkose. Cross beds in the middle and upper parts of formation indicate west to east

  7. Chemotaxonomical aspects of lower Cretaceous amber from Reconcavo Basin, Brazil

    Energy Technology Data Exchange (ETDEWEB)

    Pereira, Ricardo; Azevedo, Debora A., E-mail: ricardopereira@iq.ufrj.b, E-mail: debora@iq.ufrj.b [Universidade Federal do Rio de Janeiro (IQ/UFRJ), RJ (Brazil). Inst. de Quimica; Carvalho, Ismar S. [Universidade Federal do Rio de Janeiro (UFRJ), RJ (Brazil). Inst. de Geociencias; Fernandes, Antonio Carlos S. [Universidade Federal do Rio de Janeiro (UFRJ), RJ (Brazil). Museu Nacional. Dept. de Geologia e Paleontologia


    The chemical composition of Lower Cretaceous amber samples from Reconcavo Basin (Salvador, Bahia) was performed by GC-MS to characterize possible botanical sources. The compounds identified were hydrocarbonic and polar diterpenoids, such as abietane, dehydroabietane, tetrahydroretene, dehydroabietol, dehydroabietic acid, ferruginol and sugiol. Other diterpenoid classes were not detected as well as triterpenoids. The composition of the extracts and chemosystematic data allows relating the samples to conifers of Podocarpaceae or Cheirolepidiaceae families due to detection of ferruginol, a specific biomarker to these families. The data concerning Cretaceous amber in the Reconcavo Basin provided information concerning the presence of a resinous flora in the Maracangalha Formation sediments during the Lower Cretaceous. (author)

  8. Subsurface petroleum geology of Santa Rosa sandstone (Triassic), northeast New Mexico (United States)

    Broadhead, R. F.

    The Santa Rose Sandstone (Triassic) occurs at depths of less than 2,000 ft over most of northeast New Mexico. Two major petroleum accumulations are known to exist in it. These outcrops of oil impregnated sandstone are known as the Santa Rosa tar sands. The oil in the tar sands is viscous and heavy. The other known petroleum accumulation is a pool of heavy oil that occurs at depths of 400 ft to 800 ft in northeast Guadalupe County. Attempts are being made to recover the heavy oil with steamflooding in two small pilot fields. The lower and upper sandstone units are blanket deposits composed mostly of fine to medium grained porous sandstones and minor red siliciclastic mudstones. The middle mudstone unit is a blanket deposit composed chiefly of red siliciclastic mudstones and minor lenticular sandstones. Stratigraphic and petrographic studies indicate that good reservoirs are widespread in the lower and upper sandstone unit. The blanket geometry of the lower and upper sandstone units indicates that structure probably plays an important or even dominant role in the trapping of any undiscovered hydrocarbons in the Santa Rosa. Oil proximal to the outcrop belt of the Santa Rosa Sandstone has probably been flushed by recently recharged fresh ground water. Although the source of the oil in Santa Rosa Sandstone is not definitely known, geochemical studies point to the San Andres Formation (Permian) or possibly Pennsylanian rocks.

  9. Evolution and hydrocarbon potential of Queen Charlotte basin, Canada

    Energy Technology Data Exchange (ETDEWEB)

    McWhae, J.R.


    The structural and depositional history of the Queen Charlotte basin, a complex Tertiary rift basin with extensive coeval volcanics, involves regional geology from the Pacific plate west of the Queen Charlotte transform fault to east of the Alexander-Wrangellia terrane, based on geophysics (including newly released seismic lines), revised stratigraphy, and well data. Eight offshore wells were drilled prior to 1970 and nine shallow onshore wells were drilled in or beyond the northwestern margin of the basin. The wells provide data on porosity, seal, maturation (geothermal and vitrinite reflectance data), and oil stains in sidewall cores of the Sockeye B-10 well in the Skonun formation, here 4500 m thick. The Skonun ranges from early Miocene (17 Ma) to latest Pliocene (2 Ma) in age and the lower part is regarded as the primary hydrocarbon objective, especially in the more southern part of the basin where more favorable depositional porosities occur in paralic and shelf sandstones. Higher-than-average geothermal temperatures, locally in the southwest corner of the basin related to oblique subduction of very young oceanic crust, may reach the hydrocarbon-generating threshold in the lower Skonun marine shales. The middle Cretaceous Haida subarkose appears to be a secondary reservoir - the thickest and cleanest of the post-collision volcaniclastics. Highly organic Lower Jurassic shales provide a second, probably oil-prone, source.

  10. Mechanism of Silurian Hydrocarbon Pool Formation in the Tarim Basin

    Institute of Scientific and Technical Information of China (English)

    Liu Luofu; Guo Yongqiang; Zhao Yande; Li Yan; Chen Yuanzhuang; Chen Lixin; Pang Xiongqi; Xie Qilai; Huo Hong; Zhao Suping; Li Chao; Li Shuangwen


    There are three formation stages of Silurian hydrocarbon pools in the Tarim Basin. The widely distributed asphaltic sandstones in the Tazhong (central Tarim) and Tabei (northern Tarim) areas are the results of destruction of hydrocarbon pools formed in the first-stage, and the asphaltic sandstones around the Awati Sag were formed in the second-stage. The hydrocarbon migration characteristics reflected by the residual dry asphalts could represent the migration characteristics of hydrocarbons in the Silurian paleo-pools, while the present movable oil in the Silurian reservoirs is related to the later-stage (the third-stage) hydrocarbon accumulation.

  11. Alkylthiophenes as sensitive indicators of palaeoenvironmental changes : a study of a Cretaceous oil shale from Jordan

    NARCIS (Netherlands)

    Sinninghe Damsté, J.S.; Kohnen, M.E.L.; Rijpstra, W.I.C.; Leeuw, J.W. de


    Thirteen samples of the immature, Cretaceous Jurf ed Darawish oil shade (Jordan) were analysed quantitatively for aliphatic hydrocarbons and alkylthiophenes in the bitumens by gas chromatography-mass spectrometry after isolation of appropriate fractions.

  12. Diagenesis of shallowly buried cratonic sandstones, southwest Sinai, Egypt (United States)

    Salem, Alaa M. K.; Abdel-Wahab, Antar; McBride, Earle F.


    In spite of their age, quartzose and feldspathic Lower Carboniferous sandstones deposited on the Arabian shield in western Sinai remain friable and porous (average of 19%, maximum of 25%) except for strongly cemented ferricretes and silcretes. These fluvial and shallow-marine sandstones were not buried more than 1.5 km until Late Cretaceous and younger time, when the deepest rocks reached 2.5 km. Owing to shallow burial depths and episodic exposure, meteoric water dominated the pore system for most of geologic time: iron oxides had multiple diagenetic stages and yield Carboniferous and Late Cretaceous paleomagnetic signatures, and oxygen isotopic data for authigenic quartz, sparry calcite, and kaolinite yield meteoric signatures. The most significant diagenetic changes were: (1) cementation by iron oxide that locally reaches 40% in groundwater ferricretes; (2) reduction in porosity to 19% from an assumed original porosity 45% (19% porosity was lost by compaction and 7% by cementation); (3) generation of diagenetic quartzarenites by the loss of 7% detrital feldspar by kaolinization and dissolution; and (4) development of three thin mature silcretes apparently by thermal groundwaters. Some outcrop samples have halite and gypsum cements of young but uncertain origin: recycled from topographically higher younger rocks or from aerosols? Mature silcretes are strongly cemented by microcrystalline quartz, multiply zoned syntaxial quartz, and, originally, minor opal. Quartz overgrowths in most sandstones average only 2.2%, but display a variety of textures and in places overprint isopachous opal (now dissolved) grain coats. These features have more in common with incipient silcrete cement than normal burial quartz cement. Most silica was imported in groundwater.

  13. Geology and hydrocarbon potential of the Oued Mya basin, Algeria

    Energy Technology Data Exchange (ETDEWEB)

    Benamrane, O.; Messaoudi, M.; Messelles, H. (Sonatrach Division Exploration, Algiers (Algeria))


    The Oued Mya hydrocarbon system is located in the Sahara basin. It is one of the best producing basins in Algeria, along with the Ghadames and Illizi basins. The stratigraphic section consists of Paleozoic and Mesozoic, and is about 5000 m thick. This intracratonic basin is limited to the north by the Toughourt saddle, and to the west and east it is flanked by regional arches, Allal-Tilghemt and Amguid-Hassi Messaoud, which culminate in the super giant Hassi Messaoud and Hassi R'mel hydrocarbon accumulations, respectively, producing oil from the Cambrian sands and gas from the Trissic sands. The primary source rock in this basin is lower Silurian shale, with an average thickness of 50 m and a total organic carbon of 6% (14% in some cases). Results of maturation modeling indicate that the lower Silurian source is in the oil window. The Ordovician shales are also source rocks, but in a second order. Clastic reservoirs are in the Trissic sequence, which is mainly fluvial deposits with complex alluvial channels, and the main target in the basin. Clastic reservoirs in the lower Devonian section have a good hydrocarbon potential east of the basin through a southwest-northwest orientation. The Late Trissic-Early Jurassic evaporites that overlie the Triassic clastic interval and extend over the entire Oued Mya basin, are considered to be a super-seal evaporite package, which consists predominantly of anhydrite and halite. For paleozoic targets, a large number of potential seals exist within the stratigraphic column. This super seal does not present oil dismigration possibilities. We can infer that a large amount of the oil generated by the Silurian source rock from the beginning of Cretaceous until now still is not discovered and significantly greater volumes could be trapped within structure closures and mixed or stratigraphic traps related to the fluvial Triassic sandstones, marine Devonian sands, and Cambrian-Ordovician reservoirs.

  14. Lower Cretaceous aquifers (United States)

    U.S. Geological Survey, Department of the Interior — This data set represents the extent of the Lower Cretaceous aquifers in the states of Montana, Wyoming, South Dakota, Kansas, Nebraska, Iowa, and Minnesota..

  15. Hydrocarbon pneumonia (United States)

    Pneumonia - hydrocarbon ... Coughing Fever Shortness of breath Smell of a hydrocarbon product on the breath Stupor (decreased level of ... Most children who drink or inhale hydrocarbon products and develop ... hydrocarbons may lead to rapid respiratory failure and death.

  16. An analysis of apparent polar wander path for southwest Japan suggests no relative movement with respect to Eurasia during the Cretaceous (United States)

    Uno, Koji; Furukawa, Kuniyuki; Hatanaka, Yuri


    To test the hypothesis that southwest Japan was involved in large-scale tectonic movement with southward translation as far as 2000 km with respect to Eurasia during the Cretaceous, we examined Cretaceous paleomagnetic poles from southwest Japan to compare with those from Eurasia. Red and gray sandstone samples from the Upper Cretaceous Onogawa Group were collected from twelve sites in the Onogawa Basin in the western part of southwest Japan for paleomagnetic analysis. This group formed over the time span in which the proposed tectonic event is hypothesized to have occurred. A characteristic remanent magnetization component was isolated from red sandstone at ten sites; it is interpreted to be of primary Late Cretaceous origin. The primary directions combined with previously reported data provide a mean direction (D = 76.8°, I = 44.6°, α95 = 11.1°, N = 15) and a paleomagnetic pole (24.4°N, 202.6°E, A95 = 11.0°) for the Onogawa area. This pole is consistent with other Late Cretaceous poles from a wide area of southwest Japan, and a mean Late Cretaceous pole (28.4°N, 202.5°E, A95 = 7.5°, N = 6) is calculated and regarded as representative of this region. The Late Cretaceous pole, together with mid- and Early Cretaceous poles, constitutes an apparent polar wander path (APWP) for southwest Japan during the Cretaceous. After restoration of post-Cretaceous tectonic rotation, each Cretaceous pole for southwest Japan shows agreement with the coeval poles for Eurasia; therefore, it is unlikely that the previously proposed tectonic model that includes southward translation of southwest Japan occurred in the Late Cretaceous. Southwest Japan is considered to have behaved as a stable part of the Eurasian continental margin during the Cretaceous.

  17. Diagenesis of Cambrian and lower Carboniferous sandstones, southwest Sinai, Egypt

    Energy Technology Data Exchange (ETDEWEB)

    Abdel-Wahab, A.A.; Salem, A.M.K. [Tanta Univ., Kafr El-Sheikh (Egypt); McBride, E.F. [Univ. of Texas, Austin, TX (United States)


    Quartzose and feldspathic Cambrian and Lower Carboniferous sandstones (fluvial > marine > eolian) deposited on the Arabian shield in southwestern Sinai were not buried more than 1 to 1.5 km until Late Cretaceous and younger time, when the deepest rocks reached 2.5 km. Porosity was reduced by compaction to about 26%. Grain rearrangement was the main mechanism of compaction; intergranular pressure solution and ductile grain deformation are insignificant. Cementation by iron oxide (5%), quartz (3%), calcite (2%), kaolinite (2%) and K-feldspar (< 1%) reduced porosity to 12-15% except in silcretes and some ferricretes, where porosity was reduced to non-reservoir quality. Cements have no selectivity for certain textures or stratigraphic positions.

  18. Diagenesis of Cambrian and lower Carboniferous sandstones, southwest Sinai, Egypt

    Energy Technology Data Exchange (ETDEWEB)

    Abdel-Wahab, A.A.; Salem, A.M.K. (Tanta Univ., Kafr El-Sheikh (Egypt)); McBride, E.F. (Univ. of Texas, Austin, TX (United States))


    Quartzose and feldspathic Cambrian and Lower Carboniferous sandstones (fluvial > marine > eolian) deposited on the Arabian shield in southwestern Sinai were not buried more than 1 to 1.5 km until Late Cretaceous and younger time, when the deepest rocks reached 2.5 km. Porosity was reduced by compaction to about 26%. Grain rearrangement was the main mechanism of compaction; intergranular pressure solution and ductile grain deformation are insignificant. Cementation by iron oxide (5%), quartz (3%), calcite (2%), kaolinite (2%) and K-feldspar (< 1%) reduced porosity to 12-15% except in silcretes and some ferricretes, where porosity was reduced to non-reservoir quality. Cements have no selectivity for certain textures or stratigraphic positions.

  19. CO2 Storage Potential of the Eocene Tay Sandstone, Central North Sea, UK (United States)

    Gent, Christopher; Williams, John


    Carbon Capture and Storage (CCS) is crucial for low-carbon industry, climate mitigation and a sustainable energy future. The offshore capacity of the UK is substantial and has been estimated at 78 Gt of CO2 in saline aquifers and hydrocarbon fields. The early-mid Eocene Tay Sandstone Member of the Central North Sea (CNS) is a submarine-fan system and potential storage reservoir with a theoretical capacity of 123 Mt of CO2. The Tay Sandstone comprises of 4 sequences, amalgamating into a fan complex 125km long and 40 km at a minimum of 1500 m depth striking NW-SE, hosting several hydrocarbon fields including Gannett A, B, D and Pict. In order to better understand the storage potential and characteristics, the Tay Sandstone over Quadrant 21 has been interpreted using log correlation and 3D seismic. Understanding the internal and external geometry of the sandstone as well as the lateral extent of the unit is essential when considering CO2 vertical and horizontal fluid flow pathways and storage security. 3D seismic mapping of a clear mounded feature has revealed the youngest sequence of the Tay complex; a homogenous sand-rich channel 12 km long, 1.5 km wide and on average 100 m thick. The sandstone has porosity >35%, permeability >5 D and a net to gross of 0.8, giving a total pore volume of 927x106 m3. The remaining three sequences are a series of stacked channels and interbedded mudstones which are more quiescent on the seismic, however, well logs indicate each subsequent sequence reduce in net to gross with age as mud has a greater influence in the early fan system. Nevertheless, the sandstone properties remain relatively consistent and are far more laterally extensive than the youngest sequence. The Tay Sandstone spatially overlaps several other potential storage sites including the older Tertiary sandstones of the Cromarty, Forties and Mey Members and deeper Jurassic reservoirs. This favours the Tay Sandstone to be considered in a secondary or multiple stacked

  20. Salamanca sandstone: a good GHSR not suitable for all construction purposes. (United States)

    Pereira, Dolores; Blanco, Jose Antonio; Nespereira, Jose


    Salamanca sandstone, which in fact is an opal-cemented formation of sandstones and conglomerates, was used in the construction of many historical buildings of Salamanca old city, as well as other places nearby. Salamanca is recognized as World Heritage site since 1988, precisely because the homogeneous architecture and the use of local natural resources, as the Salamanca sandstone, the Villamayor sandstone and some local granites. The reason for using the sedimentary stone was the easy access of the resource, as the city is built on top of the Salamanca sandstone Formation, a late Cretaceous-early Palaeocene deposit. This formation consists of siliciclastic successions that were deposited in braided fluvial systems. These materials are derived from a deeply weathered Variscan basement showing ferruginous alteration that adds an aesthetic value to the global view of the natural stone. However, after several centuries, the stone has started to show serious problems due to water absorption, mainly in those places where it was used as basement of the buildings. Restoration of historical buildings should consider the use of the same original material when replacement is requested. But when this original material has been demonstrated to be not appropriate for long-term constructions, a matching and preferable natural stone should be used for replacement. There is such possibility in Salamanca and this has not have to mean the disregard of the Salamanca sandstone for other uses. The natural stone has been used for interior use and for sculpture with quality results. We present the Salamanca sandstone as a possible candidate to be taken into account as GHSR, supported by complete characterization and use recommendation.

  1. Geochemical characteristics and hydrocarbon-generating potentials of source rocks in Cretaceous Zhangwu fault depression of Songliao Basin, China%彰武断陷白垩系烃源岩地球化学特征与生烃潜力评价

    Institute of Scientific and Technical Information of China (English)

    朱建辉; 沈忠民; 李贶; 武英利; 王乐闻


    The source rocks are evaluated by using geochemical testing and the hydrocarbon-generating potential is explored in Cretaceous in the Zhangwu fault depression of Songliao Basin. The statistic analysis of organic abundance, type and maturity, and the saturated hydrocarbon chromatography of the Cretaceous source rocks in the Zhangwu fault depression show following three features. (1) The source rocks in Jiufotang Formation is thick, characterized by high organic abundance, good types and low maturity-maturity; (2) The organic matrix of this source rock is from both lower aquatic creatures and higher plants. The Jiufotang Formation was mainly from bathyal lacustrine-lacustrine lower aquatic creatures, and the Shahai Formation was from terrestrial higher plants; (3) The Jiufotang Formation and Shahai Formation source rocks firstly deposited in brackish environment and then, evolved into freshwater environment. In general, they deposited in a reduction environment. The Jiufotang Formation source rock is the main source rock in the Zhangwu fault depression with preferable-good oil potential, and then, the Shahai Formation source rocks.%利用地球化学测试手段,对松辽南部的彰武断陷白星系烃源岩进行了评价,并探讨了其生烃潜力.彰武断陷白垩系烃源岩有机质丰度、类型以及成熟度统计分析与饱和烃色谱共同反映了:(1)九佛堂组烃源岩具有厚度大、有机质丰度高、类型好、成熟度低-成熟的“三高一低”的特征.(2)烃源岩有机质母质来源于低等水生生物与高等植物混生,九佛堂组主要来自半深湖-深湖相低等水生生物,沙海组更多地混入了陆生高等植物.(3)九佛堂组-沙海组烃源岩沉积水介质环境从半咸水-淡水的演变过程,总体处于还原环境.九佛堂组烃源岩是彰武断陷中主力烃源岩,具有较好-好的生油潜力,沙海组烃源岩次之.

  2. Characteristics and their controlling factors of Cretaceous Kezilesu Group sandstone reservoirs in Akmomu gas field, northwestern Tarim Basin%塔西南阿克莫木气田白垩系克孜勒苏群砂岩储层特征及其控制因素

    Institute of Scientific and Technical Information of China (English)

    石石; 常志强; 徐艳梅; 阳建平; 初广震


    Characteristics of Kezilesu Group sandstone reservoirs and factors controlling their development are investigated based on the analysis of routine thin-sections,cast thin-sections,physical property and grain sizes. The results show that the reservoir rocks are dominanted by feldspathic litharemte and lithic sandstones with low porosity and permeability,and the pore types are mainly secondary pores including intragranular dissolved pores, intergranular dissolved pores and micropores. The mercury intrusion curve has high displacement pressure, indicating that the sorting of pore throats is poor and the pore structure feature in small pores and fine throats. The development of Kezilesu Group sandstone reservoirs in Akemomu gas field has strong correlation with grain sizes, debris content and diagenetic compaction, cementation and dissolution. For reservoir rocks were deposited under the control of braided rivers, their quality improves with grain size enlarging, debns content increasing and enhancing of dissolution. On the contrary, compaction and cementation of carbonate, clay and siliceous mineral formed during the post-diagenesis have adverse effects on reservoir rocks.%根据常规薄片、铸体薄片、常规物性和粒度分析,研究了塔西南阿克莫木气田克孜勒苏群砂岩储层的地质特征及其主控因素.结果表明,该套储层岩石类型以长石岩屑砂岩及岩屑砂岩为主;储层物性较差,为低孔、低渗储层;孔隙类型以次生孔隙为主,主要有粒内溶孔、粒间溶孔及微孔隙等;压汞曲线排驱压力较高,一般孔喉分选较差,总体具有小孔细喉的孔隙结构特征.阿克莫木气田克孜勒苏群砂岩储层发育程度与碎屑颗粒的粒度粗细,岩屑含量以及成岩阶段的压实、胶结和溶蚀作用具有较强的相关性.辫状水道控制下的碎屑颗粒越粗,岩屑含量相对越高,溶蚀作用越强,储层就越发育;压实作用及成岩后期的碳酸盐岩、

  3. 1st paleomagnetic investigation of Nubia Sandstone at Kalabsha, south Western Desert of Egypt (United States)

    Mostafa, R.; Khashaba, A.; El-Hemaly, I. A.; Takla, E. M.; Abdel Aal, E.; Odah, H.


    Two profiles have been sampled from the Nubia Sandstone at Aswan, south Western Desert: the 1st profile has been taken from Abu Aggag Formation and the 2nd one was from Sabaya Formation (23.25 °N, 32.75 °E). 136 oriented cores (from 9 sites) have been sampled. Abu Aggag Formation is of Late Cretaceous (Turonian) and Sabaya Formation is of early Cretaceous (Albian-Cenomanian). The studied rocks are subjected to rock magnetic measurements as well as demagnetization treatment. It has been found that hematite is the main magnetic mineral in both formations. Four profile sections from Abu Aggag Formation, yielded a magnetic component with D = 352.7°, I = 36.6° with α95 = 5.2° and the corresponding pole lies at Lat. = 82.8 °N and Long. = 283.1 °E. Five profile sections from Sabaya Formation, yielded a magnetic component with D = 348.6°, I = 33.3° with α95 = 5.8° and the corresponding pole lies at Lat. = 78.3 °N and Long. = 280.4 °E. The obtained paleopole for the two formations lies at Lat. = 80.5 °N and Long. = 281.7 °E. The obtaind magnetic components are considered primary and the corresponding paleopole reflects the age of Nubia Sandstone when compared with the previously obtained Cretaceous poles for Egypt.

  4. New Acid Combination for a Successful Sandstone Acidizing (United States)

    Shafiq, M. U.; Mahmud, H. K. B.; Rezaee, R.


    With the development of new enhanced oil recovery techniques, sandstone acidizing has been introduced and played a pivotal role in the petroleum industry. Different acid combinations have been applied, which react with the formation, dissolve the soluble particles; thus increase the production of hydrocarbons. To solve the problems which occurred using current preflush sandstone acidizing technology (hydrochloric acid); a new acid combination has been developed. Core flooding experiments on sandstone core samples with dimensions 1.5 in. × 3 in. were conducted at a flow rate of 2 cm3/min. A series of hydrochloric-acetic acid mixtures with different ratios were tested under 150°F temperature. The core flooding experiments performed are aimed to dissolve carbonate, sodium, potassium and calcium particles from the core samples. These experiments are followed by few important tests which include, porosity-permeability, pH value, Inductively Coupled Plasma (ICP) analysis and Nuclear Magnetic Resonance (NMR measurements). All the results are compared with the results of conventional hydrochloric acid technology. NMR and porosity analysis concluded that the new acid combination is more effective in creating fresh pore spaces and thus increasing the reservoir permeability. It can be seen from the pore distribution before and after the acidizing. Prior applying acid; the large size of pores appears most frequently in the pore distribution while with the applied acid, it was found that the small pore size is most the predominant of the pore distribution. These results are validated using ICP analysis which shows the effective removal of calcium and other positive ions from the core sample. This study concludes that the combination of acetic-hydrochloric acid can be a potential candidate for the preflush stage of sandstone acidizing at high temperature reservoirs.

  5. Sedimentologic and tectonic evolution of the Upper Cretaceous-Lower Tertiary succession at Wadi Qena, Egypt (United States)

    Soliman, Mohamed A.; Habib, Mohamed E.; Ahmed, Ezzat A.


    The Upper Cretaceous-Lower Tertiary rocks around Wadi Qena, Egypt, represent a mixed siliciclastic-carbonate-phosphorite succession including (from base to top) the Nubia Sandstone, Quseir Shale, Duwi Formation, Dakhla Shale, Tarawan Chalk, Esna Shale and Thebes Formation. Facies and microfacies investigations were carried out. The Nubia Sandstone was deposited by a fluviatile system, whereas the Quseir Shale was laid down by deltaic sedimentation. The Dakhla Shale, Esna Shale and Tarawan Chalk were formed in open marine (pelagic) realms. The Thebes Formation is a shallowing carbonate facies. Phosphorites were accumulated as lag deposits by reworking and winnowing of pre-existing phosphatic materials. The sedimentation of the Upper Cretaceous-Lower Tertiary rocks were affected by regional and local tectonics (i.e., faulting). The latter played a substantial role in the distribution of the different facies particularly the siliciclastic-carbonate facies.

  6. Effect of kaolinite as a key factor controlling the petrophysical properties of the Nubia sandstone in central Eastern Desert, Egypt (United States)

    Kassab, Mohamed A.; Abu Hashish, Mohamed F.; Nabawy, Bassem S.; Elnaggar, Osama M.


    This paper presents the results of a comprehensive petrographical and petrophysical investigation for the Late Cretaceous Nubia sandstone from Wadi Kareem in central Eastern Desert to measure their fluid flow properties and to investigate the effect of kaolinite on their petrophysical characteristics. From the petrographical analyses, scanning electron microscope 'SEM' and the X-ray diffraction 'XRD' analysis, it is shown that the studied sandstone samples are quite homogeneous in mineralogy and can be distinguished into four sedimentary microfacies: quartz arenite as a clean sandstone as well as three kaolinitic microfacies; namely they are kaolinitic quartz arenite, kaolinitic subarkose, and calcareous to kaolinitc quartz arenite. The main recognized diagenetic processes that prevailed during the post-depositional history of the Nubia sandstone are; compaction, cementation, alteration and dissolution of feldspar into kaolinite. The petrophysical potentiality of the studied sandstones was studied using the helium pycnometer, gas permeability and mercury injection confining pressure 'MICP' techniques. The investigated sandstones can be classified into three petrophysical facies with varying reservoir performances. The petrophysical behaviour of these facies is dependent mostly on their kaolinite content and its impact on porosity, permeability, irreducible water saturation, R35 (pore aperture corresponding to mercury saturation of 35% pore volume), R50 (median pore-throat radius), and MHR (the mean hydraulic radius). Therefore, the studied petrophysical facies are comparable to the distinguished petrographical facies.

  7. Uppermost Jurassic-lower cretaceous radiolarian chert from the Tanimbar Islands (Banda Arc), Indonesia (United States)

    Jasin, Basir; Haile, Neville

    This paper describes and figures Mesozoic Radiolaria from cherts in Pulau Ungar, Tanimbar Islands, eastern Indonesia. Two assemblages of Radiolaria are recognised. The lower assemblage is indicative of upper Tithonian (uppermost Jurassic) to Berriasian (lowermost Cretaceous) and the upper assemblage is of upper Valanginian to Barremian age. These are the first precise ages obtained from the Ungar Formation, a unit including sandstones with apparently good petroleum reservoir characteristics.

  8. Source rock evaluation of Cretaceous and Tertiary series in Tunisia

    Energy Technology Data Exchange (ETDEWEB)

    Oudin, J. (TOTAL-CFP, Pessac (France))


    Tunisia represents a mature hydrocarbon province with a long exploration history. In the Sfax-Kerkennah and Gabes Gulf areas, the hydrocarbon accumulations are located in series of Cretaceous and Tertiary age. To estimate the petroleum potential of this region, an evaluation of the source rock quality of the Cretaceous and Tertiary series was undertaken. In the Sfax-Kerkennak area, most of the wells studied indicate that, in the Tertiary, Ypresian and lower Lutetian show good organic content but, taking into account the potential productivity, only the Ypresian can be considered as a potential source rock. In the Cretaceous, mainly studies in the offshore area of the Gabes Gulf, the amount of organic matter is fair and it is chiefly located in Albian and Cenomanian. The Vraconian with its quite good potential is a valuable source rock. Due to the difference in the environment of deposition for these two possible source rocks - the Ypresian with its lagoon facies being carbonate and the Vraconian shaly - variations in the type of organic matter can be noted, although both are of marine origin. The hydrocarbons generated from these source rocks reflect these variations and permit them to correlate the different crude oils found in this area with their original source beds.

  9. Relationships between stylolites and cementation in sandstone reservoirs: Examples from the North Sea, U.K. and East Greenland (United States)

    Baron, Martin; Parnell, John


    The reservoir potential of hydrocarbon sandstone reservoirs may be significantly reduced by compartmentation as a result of the development of stylolites. A petrographic and fluid inclusion microthermometric study was performed on sandstones containing abundant stylolites from the Buchan, Galley and Scott Fields in the Outer Moray Firth, offshore Scotland, and from a palaeo-oil bearing sequence in East Greenland. The main objective of this study was to further constrain the temperatures and burial depths at which stylolitization occurs in sandstone reservoirs. The sandstones containing abundant stylolites are also characterized by their highly cemented nature. Numerous occurrences of quartz overgrowths clearly truncated by sutured stylolites are evident in all of the samples. Fluid inclusion microthermometry reveals that quartz cementation, which is interpreted to be coeval with stylolitization, occurred at minimum temperatures of between 86 and 136 °C. Basin modelling of the Scott and Galley Fields indicates that quartz cementation and stylolite development formed at depths greater than 2.5 km which were attained during rapid Tertiary burial. The occurrence of hydrocarbon fluid inclusions within healed microfractures orientated at high angles to the stylolites suggests that these microfractures provided pathways for hydrocarbon migration in the highly cemented, low permeability zones associated with highly stylolitized sandstones.

  10. Petrography and Diagenesis of Palaeocene -Eocene Sandstones in the Siri Canyon, Danish North Sea

    DEFF Research Database (Denmark)

    Kazerouni, Afsoon Moatari

    it is generally associated with thick coatings of opal/microquartz on the detrital framework grains.   This study also presents the occurrence and compositional variance of the authigenic zeolites in the Siri Canyon sandstones, and discusses the physico-chemical conditions, which prevailed during formation...... are microquartz, large syntaxial quartz overgrowth, calcite, and chlorite.    Chlorite forms an intra-reservoir hydrocarbon seal, and our study demonstrates the influence of early diagenetic quartz on the formation of the chlorite seal.  Early opal and microquartz are precipitated close to shale contacts...... and prevent the interaction between abundant detrital glaucony and pore-fluid and thus the formation of grain-coating berthierine.  It also preserves porosity and permeability in marginal and isolated parts of the sandstone. In other parts of the sandstone grain coating berthierine precipitated...

  11. Subtle traps in Cretaceous, Archuleta, Conejos, Mineral, and Rio Grande counties, Colorado

    Energy Technology Data Exchange (ETDEWEB)

    Brown, W.T. Jr. (Coastal Oil and Gas Corp., Denver, CO (USA))


    Regional interpretation of the stratigraphy, faulting, fracturing, and hydrodynamics in Archuleta, Conejos, Mineral, and Rio Grande Counties in southern Colorado indicates that significant reserves of hydrocarbons could exist in subtle trapping situations within the Cretaceous sequences. The presence of Price-Gramps field (7 million bbl of oil ultimate recoverable), which produces primarily from the Dakota Formation, is presently anomalous in this area but is indicative of existing hydrocarbon potential. Hydrocarbon shows from drilled wells and outcrops suggest that significant quantities of hydrocarbons are present in this area, sourced both from the San Juan basin to the south and west, and from more local areas for fractured reservoirs.

  12. Geochemical Characteristics of Aromatic Hydrocarbons of Lower Cretaceous L imestone in Cuoqin Basi%西藏措勤盆地下白垩统 海相灰岩的芳烃地球化学特征

    Institute of Scientific and Technical Information of China (English)

    任拥军; 李瑞雪


    详细总结了西藏措勤盆地下白垩统海相灰岩的芳烃地球化学特征,包括萘、菲、芴、四环、五环及三芳甾烃系列化合物。总体组成以菲系列化合物占优势,四环和五环芳烃含量较高,其它芳烃含量较少为特征。样品中惹烯含量高,硫芴/氧芴值较高,且检出了一定含量的北艹,反映出该区海相灰岩的有机母源的多样性和具有有利于有机质保存的还原沉积环境。应用萘、菲、芴、多环芳烃和三芳甾烃的各项成熟度参数分析了有机质的热演化特征,表明西藏措勤盆地下白垩统处于成熟阶段。%Field investigations have shown that the limestone in Lower Cr etaceous Duoba and Langshan Formation in Cuoqin Basin, a large scale Mesozoic m arine carbonate depositional basin in Xizang municipality of China, are potentia l hydrocarbon resource rock. Initial study indicates that there is a medium abun dance of organic matter, TOC=0.12~0.40%, chloroform bitumen"A"=0.0046~0.0054 , an d the type of organic matter is humic-sapropel. It is difficult to determine the maturity of the organic matter by means of conventional method for its relativ e lower abundance, so biomarker analysis techniques are adopted. In this paper, the geochemical characteristics of aromatic hydrocarbons from the limestone, mainly based on aromatic hydrocarbons analytical data, are discussed in detail.   Various series of aromatic hydrocarbons have been found from the samples: naphth ale ne, phenanthrenes( for example retene and pimantrene), biphenyl,dibenzofuran, fluorene, dibenzothiophen,benzonaphthathiophene,fluoranthene,benzofluoranthen es,pyrene,benzo〔e〕pyrene,chrysene,perylene, tri-aromatic steroids and soo n. . Among them the majority are phenanthrene series,then rectcyclo and pentacyclo aromatic hydrocarbons, and each of the rest has a little quantity. Various ge och emical parameters of these aromatic hydrocarbons are

  13. New geochronologic and stratigraphic evidence confirms the paleocene age of the dinosaur-bearing ojo alamo sandstone and animas formation in the San Juan Basin, New Mexico and Colorado (United States)

    Fassett, J.E.


    Dinosaur fossils are present in the Paleocene Ojo Alamo Sandstone and Animas Formation in the San Juan Basin, New Mexico, and Colorado. Evidence for the Paleo-cene age of the Ojo Alamo Sandstone includes palynologic and paleomagnetic data. Palynologic data indicate that the entire Ojo Alamo Sandstone, including the lower dinosaur-bearing part, is Paleocene in age. All of the palynomorph-productive rock samples collected from the Ojo Alamo Sandstone at multiple localities lacked Creta-ceous index palynomorphs (except for rare, reworked specimens) and produced Paleocene index palynomorphs. Paleocene palynomorphs have been identified strati-graphically below dinosaur fossils at two separate localities in the Ojo Alamo Sand-stone in the central and southern parts of the basin. The Animas Formation in the Colorado part of the basin also contains dinosaur fossils, and its Paleocene age has been established based on fossil leaves and palynology. Magnetostratigraphy provides independent evidence for the Paleocene age of the Ojo Alamo Sandstone and its dinosaur-bearing beds. Normal-polarity magnetochron C29n (early Paleocene) has been identified in the Ojo Alamo Sandstone at six localities in the southern part of the San Juan Basin. An assemblage of 34 skeletal elements from a single hadrosaur, found in the Ojo Alamo Sandstone in the southern San Juan Basin, provided conclusive evidence that this assemblage could not have been reworked from underlying Cretaceous strata. In addition, geochemical studies of 15 vertebrate bones from the Paleocene Ojo Alamo Sandstone and 15 bone samples from the underlying Kirtland Formation of Late Creta-ceous (Campanian) age show that each sample suite contained distinctly different abundances of uranium and rare-earth elements, indicating that the bones were miner-alized in place soon after burial, and that none of the Paleocene dinosaur bones ana-lyzed had been reworked. ?? U.S. Geological Survey, Public Domain April 2009.

  14. Fission track dating of mesozoic sandstones and its tectonic significance in the Eastern Sichuan Basin, China

    Energy Technology Data Exchange (ETDEWEB)

    Shen Chuanbo, E-mail: cugshen@yahoo.c [Key Laboratory of Tectonics and Petroleum Resources, China University of Geosciences, Ministry of Education, Wuhan 430074 (China); Faculty of Earth Resources, China University of Geosciences, Wuhan, Hubei Province 430074 (China); Mei Lianfu [Key Laboratory of Tectonics and Petroleum Resources, China University of Geosciences, Ministry of Education, Wuhan 430074 (China); Xu Sihuang [Faculty of Earth Resources, China University of Geosciences, Wuhan, Hubei Province 430074 (China)


    To establish the tectonic evolution of the eastern Sichuan basin, apatite fission track dating and time-temperature thermal history modeling were carried to analyze on 11 samples collected from Jurassic sandstones. The results indicate that the cooling and exhumation process of the eastern Sichuan basin can be divided into three stages since Cretaceous, (1) a rapid cooling phase between approx100 and approx70 Ma, (2) following by a period of relative thermal stability phase between approx70 and approx15 Ma, (3) and then a new rapid cooling stage after approx15 Ma. Two rapid cooling events imply that the eastern Sichuan basin once underwent two tectonic movements since Cretaceous. The first rapid cooling is associated with Mesozoic tectonic reactivation beginning at 100 Ma, which result in folds and faults of the eastern Sichuan basin. The second tectonic movement occurred at 15 Ma, which is related to denudation by compression resulting from the eastward growth of Tibetan plateau uplift.

  15. Current Situation and Application in Coal- Generated Hydrocarbons

    Institute of Scientific and Technical Information of China (English)

    YANG Guang; XU Hongdong


    The characteristics and research methods of terrigenous organic hydrocarbon - generated source rock in coal measures are studied in this thesis. After abundance of organic matters, pyrolysis parameter of rocks and hydrocarbon generated capacity of macerals are basically discussed in coal measures of the Cretaceous Muleng- Chengzihe formation in Suibin depression in Sanjang basin, the hydrocarbon generated grade in coal- generated source rock is ascertained in this depression. At last, we think that it is a main attack prospect in coal - generated hydrocarbons study in the future to research the macerals of coal measures organic source rock and to build a criterion to classify the coal- generated hydrocarbons in Northeast region.

  16. Migrated hydrocarbons in exposure of Maastrichtian nonmarine strata near Saddle Mountain, lower Cook Inlet, Alaska (United States)

    LePain, D.L.; Lillis, P.G.; Helmold, K.P.; Stanley, R.G.


    Magoon and others (1980) described an 83-meter- (272-foot-) thick succession of Maastrichtian (Upper Cretaceous) conglomerate, sandstone, mudstone, and coal exposed on the south side of an unnamed drainage, approximately 3 kilometers (1.8 miles) east of Saddle Mountain in lower Cook Inlet (figs. 1 and 2). The initial significance of this exposure was that it was the first reported occurrence of nonmarine rocks of this age in outcrop in lower Cook Inlet, which helped constrain the Late Cretaceous paleogeography of the area and provided important information on the composition of latest Mesozoic sandstones in the basin. The Saddle Mountain section is thought to be an outcrop analog for Upper Cretaceous nonmarine strata penetrated in the OCS Y-0097 #1 (Raven) well, located approximately 40 kilometers (25 miles) to the south–southeast in Federal waters (fig. 1). Atlantic Richfield Company (ARCO) drilled the Raven well in 1980 and encountered oil-stained rocks and moveable liquid hydrocarbons between the depths of 1,760 and 3,700 feet. Completion reports on file with the Bureau of Ocean Energy Management (BOEM; formerly Bureau of Ocean Energy Management, Regulation and Enforcement, and prior to 2010, U.S. Minerals Management Service) either show flow rates of zero or do not mention flow rates. A fluid analysis report on file with BOEM suggests that a wireline tool sampled some oil beneath a 2,010-foot diesel cushion during the fl ow test of the 3,145–3,175 foot interval, but the recorded fl ow rate was still zero (Kirk Sherwood, written commun., January 9, 2012). Further delineation and evaluation of the apparent accumulation was never performed and the well was plugged and abandoned. As part of a 5-year comprehensive evaluation of the geology and petroleum systems of the Cook Inlet forearc basin, the Alaska Division of Geological & Geophysical Surveys obtained a research permit from the National Park Service to access the relatively poorly understood

  17. Heavy mineral sorting in downwards injected Palaeocene sandstone, Siri Canyon, Danish North Sea

    DEFF Research Database (Denmark)

    Kazerouni, Afsoon Moatari; Friis, Henrik; Svendsen, Johan Byskov


    near the Danish Central Graben of the North Sea hydrocarbon province. The emplacement of large-scale injectite complexes has been commonly attributed to seismic activity and consequent sand liquefaction. However, due to very small differences in textural and compositional properties, and the lack...... /geochemical distinction between "in situ" sandstones and their related injectites, especially where primary sedimentary structures are removed by fluidization or minor remobilization....

  18. Direct radiometric dating of hydrocarbon deposits using rhenium-osmium isotopes. (United States)

    Selby, David; Creaser, Robert A


    Rhenium-osmium (Re-Os) data from migrated hydrocarbons establish the timing of petroleum emplacement for the giant oil sand deposits of Alberta, Canada, at 112 +/- 5.3 million years ago. This date does not support models that invoke oil generation and migration for these deposits in the Late Cretaceous. Most Re-Os data from a variety of deposits within the giant hydrocarbon system show similar characteristics, supporting the notion of a single source for these hydrocarbons. The Re-Os data disqualify Cretaceous rocks as the primary hydrocarbon source but suggest an origin from older source rocks. This approach should be applicable to dating oil deposits worldwide.

  19. Microspectroscopic evidence of cretaceous bone proteins.

    Directory of Open Access Journals (Sweden)

    Johan Lindgren

    Full Text Available Low concentrations of the structural protein collagen have recently been reported in dinosaur fossils based primarily on mass spectrometric analyses of whole bone extracts. However, direct spectroscopic characterization of isolated fibrous bone tissues, a crucial test of hypotheses of biomolecular preservation over deep time, has not been performed. Here, we demonstrate that endogenous proteinaceous molecules are retained in a humerus from a Late Cretaceous mosasaur (an extinct giant marine lizard. In situ immunofluorescence of demineralized bone extracts shows reactivity to antibodies raised against type I collagen, and amino acid analyses of soluble proteins extracted from the bone exhibit a composition indicative of structural proteins or their breakdown products. These data are corroborated by synchrotron radiation-based infrared microspectroscopic studies demonstrating that amino acid containing matter is located in bone matrix fibrils that express imprints of the characteristic 67 nm D-periodicity typical of collagen. Moreover, the fibrils differ significantly in spectral signature from those of potential modern bacterial contaminants, such as biofilms and collagen-like proteins. Thus, the preservation of primary soft tissues and biomolecules is not limited to large-sized bones buried in fluvial sandstone environments, but also occurs in relatively small-sized skeletal elements deposited in marine sediments.

  20. Microfabric and anisotropy of elastic waves in sandstone - An observation using high-resolution X-ray microtomography (United States)

    Kahl, Wolf-Achim; Hinkes, Robert; Feeser, Volker; Holzheid, Astrid


    Petrophysical experiments, using acoustic velocities to characterise anisotropies of mechanical behaviour of rocks are of essential relevance to understand the geomechanical behaviour of sandstone reservoirs under changing stress fields. Here, we present high-resolution X-ray microtomography (μ-CT) as a supplementary research tool to interpret anisotropic ultrasound velocities in sandstones with variation of isotopic stress. Specimens of two Lower Cretaceous sandstones (localities Bentheim and Obernkirchen, both Germany) have been used in petrophysical laboratory experiments under dry conditions to study ultrasonic sound velocities (frequency of signal input 1 MHz). Subsequently, oriented micro-plugs drilled from the sandstone samples were investigated using high-resolution X-ray microtomography. By means of image processing of the reconstructed scan images, geometric attributes such as mean structural thickness, orientation and tortuosity were evaluated from the μ-CT data for both pore space and grain skeleton. Our observations clearly indicate the different roles of pore space and grain skeleton in regard to the propagation of ultrasonic waves: because the pores do not transmit the waves, it was sufficient to investigate the average thickness of this fabric element. In contrast, as the ultrasonic waves traverse the rock via the adjacent grains, it was necessary to survey the actual travel lengths of seismic waves in the sandstone grain skeleton.

  1. Characteristics of bleaching of sandstone in northeast of Ordos Basin and its relationship with natural gas leakage

    Institute of Scientific and Technical Information of China (English)

    MA; YanPing; LIU; ChiYang; ZHAO; JunFeng; HUANG; Lei; YU; Lin; WANG; JianQiang


    Bleaching of sandstone has significant applications to tracing hydrocarbon pathways and evaluating the scale of natural gas seepage. Bleaching of sandstones in the northeast of Ordos Basin is mainly distributed in the Mesozoic Yan'an Formation. Studying on petrology, major elements, REEs and trace elements of bleached sandstones and comparing with adjacent sandstones, combining with geologic-geochemical evidences of gas seepage in the northeast of the basin, the bleached sandstones are formed in the acid environment and reducing fluids. Characteristics of petrology show that the contents of kaolinite are high and the color of margin of ferric oxide minerals is lighter than that of the center. Major elements of sandstone samples show high contents of Al2O3 and low ratio of Fe3+/Fe2+. The TFe2O3 content of the bleached sandstone is lower than that of red rock. REE data show that bleached sandstones have low ∑REE contents and Eu-depleted and slightly Ce-enriched. Trace elements show that the bleached sandstones enrich in Co, deplete in Sr, and slightly enrich in Zr and Hf which are close to the values for the green alteration sandstones, and slightly lower than ore-bearing sandstones. Geochemical characteristics of oil-bearing sandstone in the northern basin suggest that the oil-shows are formed by matured Carboniferous-Permian coal bed methane escaping to the surface, and natural gas in field could migrate to the north margin of the basin. The δ13C (PDB) andδ18O(PDB) values of calcite cement in the study area range from -11.729‰ to -10.210‰ and -14.104‰ to -12.481‰, respectively. Theδ13C (PDB) values less than -10‰ imply the carbon sources part from organic carbon. Comprehensive study suggests that the gas leakage has occurred in the northeastern basin, which is responsible for bleaching of the sandstone on top of the Yan'an Formation.

  2. The Qishn Formation, Yemen: lithofacies and hydrocarbon habitat

    Energy Technology Data Exchange (ETDEWEB)

    Beydoun, Z.R. (American Univ., Beirut (Lebanon)); Bamahmoud, M.O.; Nani, A.S.O. (Ministry of Oil and Mineral Resources, Sana' a (Yemen, Republic of). Petroleum Exploration and Production Board)


    The Barremian-Aptian Qishn Formation of Yemen is broadly described in the context of its role as the lowest widespread transgressive unit of the Cretaceous system in the country and of the two laterally equivalent lithofacies groups that reflect the advance of the Cretaceous sea from east to west. This is undertaken against the background to the tectonic events that preceded its deposition and those that followed it during the remainder of the Cretaceous, so as to better understand its hydrocarbon habitat. (Author)

  3. The hydrocarbon prospectivity of lower oligocene deposits in the Maragh Trough, Se Sirt Basin, Libya

    Energy Technology Data Exchange (ETDEWEB)

    Gruenwald, R. [Wintershall Libya, Tripoli (Libya)


    The main phase of rifting the Sirt Basin (Libya) had ceased by the mid-Cretaceous but later Alpine-related tectonic pulses in the late Eocene resulted in northward tilting of the basin. In the Maragh Trough (SE Sirt basin), a regional unconformity consequently separates Eocene carbonates from the overlying Oligocene succession. The unconformity marks a change from Eocene fully-marine sedimentation to more mixed, shallow-marine type deposition in the Oligocene. A regional transgression re-established fully marine conditions in the Miocene. Deeply-buried (Triassic) source rocks in the Maragh Trough reached peak oil generation during the Oligocene. Two potential reservoir intervals have been identified: upper Eocene rudstones of the Augila Formation, and unconformably-overlying sandstones of the Lower Oligocene Arida Formation. Mid-Oligocene shales provide a regional seal. Facies distributions and reservoir properties are related to rift-related structural highs. Despite the absence of a nearby source kitchen, Upper Eocene carbonates have been found to be oil-bearing in the Maragh Trough at wells D1- and F1-96. This indicates that hydrocarbons have migrated along graben-bounding faults from deeply-buried source rocks to platform and sub-platform areas. Traps are of combined structural and stratigraphic type. (author)

  4. Hydrocarbon-Derived Carbonate Cements of Subsurface Origin in the Vulcan Sub-Basin, Timor Sea

    Directory of Open Access Journals (Sweden)

    Shou-Yeh Gong


    Full Text Available Localized carbonate cementation occurs in the Eocene Grebe Sandstone of the Vulcan Sub-basin, Timor Sea, Australia. The cements have been previously interpreted as originating from microbial methane oxidation and sulfate reduction in a shallow subsurface environment and were related to hydrocarbon leakage. Here we reassess these localized carbonate cements in the Grebe Sandstone, and reported new findings. Petrography shows that there are two facies of sands in the Grebe Sandstone: (1 cemented, mostly fine-grained sands; and (2 loose, often coarse-grained sands. In addition, two types of carbonate matrix occur in the Grebe Sandstone: (1 spars to microspars in calcareous, fine-grained sandstones; and (2 micritic to microsparry matrix associated with limestone grains. Stable carbon isotopic values reveal that only the cements associated with sandstones were probably hydrocarbon-derived, and the resultant mineral is mainly calcite. Petrographic attributes and Mn+2 and Co+2 compositions of these cements differ significantly from those of modern cold-seep carbonates at or near the sea floor. Moreover, the hydrocarbon-derived carbonate mineralization only occurs in the fine-grained sands, not in the coarse-grained sands. In other word, the cementation was not only dependent on hydrocarbon leakage but also on the lithofacies of the host rock. We propose that the extent of hydrocarbon-related cementation alone cannot be used to evaluate the trap integrity as has been previously suggested.

  5. Rate type isotach compaction of consolidated sandstone

    NARCIS (Netherlands)

    Waal, J.A. de; Thienen-Visser, K. van; Pruiksma, J.P.


    Laboratory experiments on samples from a consolidated sandstone reservoir are presented that demonstrate rate type compaction behaviour similar to that observed on unconsolidated sands and soils. Such rate type behaviour can have large consequences for reservoir compaction, surface subsidence and

  6. Investigating Controls on Sedimentation Through Interpretation of the Syntectonic Cretaceous-Paleogene Sedimentary Record in the San Juan Basin (New Mexico, U.S.A.) (United States)

    Hobbs, K.; Weissmann, G. S.; Fawcett, P. J.


    The Cretaceous/Paleogene boundary in the southwestern San Juan Basin is bracketed by the mudstone-dominated Cretaceous Kirtland Formation, the sandstone-dominated Paleocene Ojo Alamo Sandstone, and the mudstone-dominated Paleocene lower Nacimiento Formation. Geochemical trends of fluvial mudstones from these units indicate changing sedimentary source areas through time. While the Kirtland and Nacimiento Formations represent periods of high accommodation within the San Juan Basin, the Ojo Alamo Sandstone represents a period of low accommodation and general reworking and transport by southeast-flowing paleorivers. The Kirtland and Nacimiento Formations thin and fine away from their interpreted source area whereas the Ojo Alamo Sandstone thickens and fines away from the source area. Here we investigate the enigmatic sedimentary architecture of the Ojo Alamo Sandstone, geochemical evidence for a changing source area through this time period, and the complex relationships between sedimentation, source area, accommodation, and basin tectonic evolution. Incorporating new measured sections, petrographic analyses, geochemical trends, and stratigraphic relationships, we propose that the Ojo Alamo Sandstone represents an anomalous short period of low accommodation in the San Juan Basin during the early Laramide Orogeny and explore possible intra- and extra-basinal tectonic, climatic, and sedimentologic explanations as well as implications for understanding the evolution of the basin.

  7. Experimental strain analysis of Clarens Sandstone colonised by endolithic lichens

    Directory of Open Access Journals (Sweden)

    D. Wessels


    Full Text Available Endolithic lichens occur commonly on Clarens Sandstone in South Africa, where they significantly contribute to the weathering of sandstone by means of mechanical and chemical weathering processes. This preliminary investigation reports on the success- ful use of strain gauges in detecting strain differences between sandstone without epilithic lichens and sandstone colonised by the euendolithic lichen Lecidea aff. sarcogynoides Korb. Mechanical weathering, expressed as strain changes, in Clarens Sandstone was studied during the transition from relatively dry winter to wet summer conditions. Daily weathering of sandstone due to thermal expansion and contraction of colonised and uncolonised sandstone could be shown. Our results show that liquid water in sandstone enhances the mechanical weathering of uncolonised Clarens Sandstone while water in the gaseous phase enhances mechanical weathering of sandstone by euendolithic lichens.

  8. Comparative Study of Basins within Palaeogene Seaway in East China and Cretaceous Seaway in North America and Its Reservoir Significance

    Institute of Scientific and Technical Information of China (English)

    Wu Xiantao


    The well known Cretaceous seaway in North America was recognized in the middle of the last century and the Palaeogene seaway in East China was proposed by the author recently. The two seaways located on the opposite sides of North Pacific Ocean may be not a coincidence,and a comparative study was made in this paper. The results show that the two seaways inundated basins share several similarities particularly in basin origin,filling processes and reservoir facies. It is suggested that reservoir facies of estuarine sandstone and shelf bar sandstone related to sea level fluctuation,which are well developed in the Cretaceous seaway covered basins in North America might have been also developed here in Palaeogene seaway inundated basins in East China. Therefore it is worth paying more attention to finding these new reservoir facies on this side of the Pacific ocean. Evidences of sedimentology and ichnology indicate that good prospects are likely.

  9. Cretaceous Crocodyliforms from the Sahara

    Directory of Open Access Journals (Sweden)

    Paul Sereno


    Full Text Available Diverse crocodyliforms have been discovered in recent years in Cretaceous rocks on southern landmasses formerly composing Gondwana.  We report here on six species from the Sahara with an array of trophic adaptations that significantly deepen our current understanding of African crocodyliform diversity during the Cretaceous period.  We describe two of these species (Anatosuchus minor, Araripesuchus wegeneri from nearly complete skulls and partial articulated skeletons from the Lower Cretaceous Elrhaz Formation (Aptian-Albian of Niger. The remaining four species (Araripesuchus rattoides sp. n., Kaprosuchus saharicus gen. n. sp. n., Laganosuchus thaumastos gen. n. sp. n., Laganosuchus maghrebensis gen. n. sp. n. come from contemporaneous Upper Cretaceous formations (Cenomanian in Niger and Morocco.

  10. 1st paleomagnetic investigation of Nubia Sandstone at Kalabsha, south Western Desert of Egypt

    Directory of Open Access Journals (Sweden)

    R. Mostafa


    Full Text Available Two profiles have been sampled from the Nubia Sandstone at Aswan, south Western Desert: the 1st profile has been taken from Abu Aggag Formation and the 2nd one was from Sabaya Formation (23.25 °N, 32.75 °E. 136 oriented cores (from 9 sites have been sampled. Abu Aggag Formation is of Late Cretaceous (Turonian and Sabaya Formation is of early Cretaceous (Albian–Cenomanian. The studied rocks are subjected to rock magnetic measurements as well as demagnetization treatment. It has been found that hematite is the main magnetic mineral in both formations. Four profile sections from Abu Aggag Formation, yielded a magnetic component with D = 352.7°, I = 36.6° with α95 = 5.2° and the corresponding pole lies at Lat. = 82.8 °N and Long. = 283.1 °E. Five profile sections from Sabaya Formation, yielded a magnetic component with D = 348.6°, I = 33.3° with α95 = 5.8° and the corresponding pole lies at Lat. = 78.3 °N and Long. = 280.4 °E. The obtained paleopole for the two formations lies at Lat. = 80.5 °N and Long. = 281.7 °E. The obtaind magnetic components are considered primary and the corresponding paleopole reflects the age of Nubia Sandstone when compared with the previously obtained Cretaceous poles for Egypt.

  11. Natural gas accumulations in low-permeability Tertiary, and Cretaceous (Campanian and Maastrichtian) rock, Uinta Basin, Utah. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Fouch, T.D.; Wandrey, C.J.; Pitman, J.K.; Nuccio, V.F.; Schmoker, J.W.; Rice, D.D.; Johnson, R.C.; Dolton, G.L.


    This report characterizes Upper Cretaceous Campanian and Maastrichtian, and lower Tertiary gas-bearing rocks in the Uinta Basin with special emphasis on those units that contain gas in reservoirs that have been described as being tight. The report was prepared for the USDOE whose Western Tight Gas Sandstone Program cofunded much of this research in conjunction with the US Geological Survey`s Evolution of Sedimentary Basins, and Onshore Oil and Gas Programs. (VC)

  12. Natural gas accumulations in low-permeability Tertiary, and Cretaceous (Campanian and Maastrichtian) rock, Uinta Basin, Utah

    Energy Technology Data Exchange (ETDEWEB)

    Fouch, T.D.; Wandrey, C.J.; Pitman, J.K.; Nuccio, V.F.; Schmoker, J.W.; Rice, D.D.; Johnson, R.C.; Dolton, G.L.


    This report characterizes Upper Cretaceous Campanian and Maastrichtian, and lower Tertiary gas-bearing rocks in the Uinta Basin with special emphasis on those units that contain gas in reservoirs that have been described as being tight. The report was prepared for the USDOE whose Western Tight Gas Sandstone Program cofunded much of this research in conjunction with the US Geological Survey's Evolution of Sedimentary Basins, and Onshore Oil and Gas Programs. (VC)

  13. "Sydney sandstone": Heritage Stone from Australia (United States)

    Cooper, Barry; Kramar, Sabina


    Sydney is Australia's oldest city being founded in 1788. The city was fortunate to be established on an extensive and a relatively undeformed layer of lithified quartz sandstone of Triassic age that has proved to be an ideal building stone. The stone has been long identified by geologists as the Hawkesbury Sandstone. On the other hand the term "Sydney sandstone" has also been widely used over a long period, even to the extent of being utilised as the title of published books, so its formal designation as a heritage stone will immediately formalise this term. The oldest international usage is believed to be its use in the construction of the Stone Store at Kerikeri, New Zealand (1832-1836). In the late 19th century, public buildings such as hospitals, court houses as well as the prominent Sydney Town Hall, Sydney General Post Office, Art Gallery of New South Wales, State Library of New South Wales as well as numerous schools, churches, office building buildings, University, hotels, houses, retaining walls were all constructed using Sydney sandstone. Innumerable sculptures utilising the gold-coloured stone also embellished the city ranging from decorative friezes and capitals on building to significant monuments. Also in the late 19th and early 20th century, Sydney sandstone was used for major construction in most other major Australian cities especially Melbourne, Adelaide and Brisbane to the extent that complaints were expressed that suitable local stone materials were being neglected. Quarrying of Sydney sandstone continues today. In 2000 it was recorded noted that there were 33 significant operating Sydney sandstone quarries including aggregate and dimension stone operations. In addition sandstone continues to be sourced today from construction sites across the city area. Today major dimension stone producers (eg Gosford Quarries) sell Sydney sandstone not only into the Sydney market but also on national and international markets as cladding and paving products

  14. Lower Cretaceous calcareous nannofossils from the Southern Apuseni Mountains, Romania

    Directory of Open Access Journals (Sweden)

    Ana-Maria Vulc


    Full Text Available We investigated Lower Cretaceous calcareous nannofossils from Southern Apuseni Mts. The studied section from Bucium Cerbu quarry is characterized by flysch deposits (rhythmical interbedded marls and sandstones, which were assigned to the Căbeşti Formation. The studied nannofossil assemblages yielded a high diversity. The Early Aptian age of the studied deposits was assigned based on both the Tethyan and Boreal calcareous nannofossil zonations. Several reworked Valanginian nannofossils were also observed in the Early Aptian in situ nannofloras. The nannofloras are dominated by tethyan and cosmopolitan species. Besides Boreal species are also present. The presence of boreal taxa (e.g. Kokia borealis, K. stelatta in the Tethyan Realm reflects the palaeobiogeographical distribution and the biotic changes between Tethys and Boreal Realms in the Southern Apuseni Mts. In the studied assemblages, the dominant species are Diazomatolithus lehmanii and Watznaueria barnesiae, which can reflect a high fertility in the surface water masses.

  15. The distribution of Cretaceous and Paleocene deep-water reservoirs in the Norwegian Sea basins

    Energy Technology Data Exchange (ETDEWEB)

    Vergara, L. [RWE-DEA AG, Hamburg (Germany); Wreglesworth, I. [IWA Associates, Colwyn Bay (United Kingdom); Trayfoot, M. [PGS Reservoir Consultants, Lysaker (Norway); Richardsen, G. [RWE-DEA Norge, Oslo (Norway)


    Facies maps for selected Cretaceous and Paleocene deep-water sandstone reservoirs in the Norwegian Sea constitute an exploration tool and allow description of the basin infill in relation to tectonic phases. Sequences K40 (middle-late Albian) and K60 (middle-late Cenomanian) formed in an immature basin where most of the fan systems and slumps were derived from local highs. Sequence K80 (Coniacian-late Santonian) contains sandstones interpreted to be slumped deposits in parts of the Halten and Donna terraces (Lysing Formation), but with fans of widespread extent in the Voring and northern More Basin. The K85-K90 sequence set (early Santonian-late Campanian) contains sandstones equivalent to the Nise Formation that are the main potential reservoirs in the Voring Basin; they were fed by multiple entry points and developed into areally extensive basin floor thicks. Sequence Pg10 (Danian-Selandian: 'Egga' Member) is interpreted to comprise a basin floor fan in the Ormen Lange discovery. During this cycle the Halten Terrace rotated eastwards exposing Upper Cretaceous mudstones. Vast amounts of sediment were deposited in the western More and Voring Basin around new exposed areas. (author)

  16. Upper Jurassic to Lower Cretaceous(?) synorogenic sedimentary rocks in the southern Spring Mountains, Nevada (United States)

    Carr, Michael D.


    A newly recognized sequence of Upper Jurassic to Lower Cretaceous(?) terrigenous rocks in the Good-springs district, Nevada, was deposited during the emplacement of the Contact thrust plate. Two facies are recognized: (1) interbedded conglomerate and sandstone derived from Mesozoic igneous and terrigenous platform rocks and (2) interbedded carbonate and sandstone-clast conglomerate, quartz sandstone, and red shale. No igneous detritus occurs in the facies with carbonate-clast conglomerate. Carbonate clasts could only have been derived from the Paleozoic carbonate sequence, which was exposed in the area by latest Jurassic to earliest Cretaceous thrusting. The age of rocks from a volcanic unit within the synorogenic sequence was determined radiometrically to be 150 ± 10 m.y. (K-Ar on biotite). The sequence was deposited disconformably on deeply eroded rocks of the early Mesozoic platform and ultimately overridden from the west by the Contact thrust plate. Information from the sequence corroborates previously reported regional data regarding the timing and nature of the Contact-Red Springs thrust event. *Present address: U.S. Geological Survey, 345 Middlefield Road, Menlo Park, California 94025

  17. Upper Cretaceous bioturbated fine-to-medium sands: A problem for deep-water exploration in Campos Basin, Offshore Brazil

    Energy Technology Data Exchange (ETDEWEB)

    Carminatti, M.; Zimmermann, L.; Jahnert, R.; Pontes, C.


    The presence of bioturbation in oil-prone turbidite deposits has detained a better exploration of upper Cretaceous siliciclastic reservoirs in Campos Basin. Bioturbated sandstones have degraded their permo-porosity with impact in oil production. They occur associated to unbioturbated sandstones with similar seismic amplitude, becoming difficult to separate them in seismic mapping. A comprehensive study in order to reduce the exploratory risk must consider firstly the recognition of genetic facies association through cores, and secondly the calibration of sonic well-logs and seismic velocity sections with rock data. This study deals with sedimentary facies association. The range of main facies in such reservoirs includes: (1) medium-to-coarse siliciclastic sandstone with cross stratification; (2) fine-to-medium massive sandstone with thin traction carpets, bioturbated by opportunistic ichnofabrics and, (3) bioturbated, muddy, fine-to-medium, quartz-feldspatic and glauconitic sandstone over 60 in thick. The genetic facies associations suggest that the sandwich reservoirs were formed by high density turbidite currents deposited en masse or by thin traction carpets. The bioturbated sandstone was originated by reworking of bottom currents rich in nutrients and oxygen. Detritic and biogenic glauconite covered and/or filled bioturbations indicate a basinward movement of the bottom currents. The successive alternation of high-energy with low-energy ichnofabrics reflects cyclic variations in current velocities.

  18. Paleomagnetic study of Jurassic and Cretaceous rocks from the Mixteca terrane (Mexico) (United States)

    Böhnel, Harald


    Three sites from Cretaceous limestone and Jurassic sandstone in northern Oaxaca, Mexico, were studied paleomagnetically. Thermal demagnetization isolated site-mean remanence directions which differ significantly from the recent geomagnetic field. The paleopole for the Albian-Cenomanian Morelos formation is indistinguishable from the corresponding reference pole for stable North America, indicating tectonic stability of the Mixteca terrane since the Cretaceous. Rock magnetic properties and a positive reversal test for the Bajocian Tecomazuchil sandstone suggest that the remanence could be of primary origin, although no fold test could be applied. The Tecomazuchil paleopole is rotated 10°±5° clockwise and displaced 24°±5° towards the study area, with respect to the reference pole for stable North America. Similar values were found for the Toarcien-Aalenian Rosario Formation, with 35°±6° clockwise rotation and 33°±6° latitudinal translation. These data support a post-Bajocian southward translation of the Mixteca terrane by around 25°, which was completed in mid-Cretaceous time.

  19. An Effective Acid Combination for Enhanced Properties and Corrosion Control of Acidizing Sandstone Formation (United States)

    Umer Shafiq, Mian; Khaled Ben Mahmud, Hisham


    To fulfill the demand of the world energy, more technologies to enhance the recovery of oil production are being developed. Sandstone acidizing has been introduced and it acts as one of the important means to increase oil and gas production. Sandstone acidizing operation generally uses acids, which create or enlarge the flow channels of formation around the wellbore. In sandstone matrix acidizing, acids are injected into the formation at a pressure below the formation fracturing pressure, in which the injected acids react with mineral particles that may restrict the flow of hydrocarbons. Most common combination is Hydrofluoric Acid - Hydrochloric with concentration (3% HF - 12% HCl) known as mud acid. But there are some problems associated with the use of mud acid i.e., corrosion, precipitation. In this paper several new combinations of acids were experimentally screened to identify the most effective combination. The combinations used consist of fluoboric, phosphoric, formic and hydrofluoric acids. Cores were allowed to react with these combinations and results are compared with the mud acid. The parameters, which are analyzed, are Improved Permeability Ratio, strength and mineralogy. The analysis showed that the new acid combination has the potential to be used in sandstone acidizing.

  20. Maps showing thermal maturity of Upper Cretaceous marine shales in the Wind River Basin, Wyoming (United States)

    Finn, Thomas M.; Pawlewicz, Mark J.


    The Wind River Basin is a large Laramide (Late Cretaceous through Eocene) structural and sedimentary basin that encompasses about 7,400 square miles in central Wyoming. The basin is bounded by the Washakie Range, Owl Creek, and southern Bighorn Mountains on the north, the Casper arch on the east and northeast, the Granite Mountains on the south, and the Wind River Range on the west. Important conventional and unconventional oil and gas resources have been discovered and produced from reservoirs ranging in age from Mississippian through Tertiary. It has been suggested that various Upper Cretaceous marine shales are the principal hydrocarbon source rocks for many of these accumulations. Numerous source rock studies of various Upper Cretaceous marine shales throughout the Rocky Mountain region have led to the conclusion that these rocks have generated, or are capable of generating, oil and (or) gas. With recent advances and success in horizontal drilling and multistage fracture stimulation there has been an increase in exploration and completion of wells in these marine shales in other Rocky Mountain Laramide basins that were traditionally thought of only as hydrocarbon source rocks. Important parameters that control hydrocarbon production from shales include: reservoir thickness, amount and type of organic matter, and thermal maturity. The purpose of this report is to present maps and a structural cross section showing levels of thermal maturity, based on vitrinite reflectance (Ro), for Upper Cretaceous marine shales in the Wind River Basin.

  1. Geological and Petrophysical Characterization of the Ferron Sandstone for 3-D Simulation of a Fluvial-Deltaic Reservoir

    Energy Technology Data Exchange (ETDEWEB)

    Chidsey, Jr, Thomas C.


    The objective of the Ferron Sandstone project was to develop a comprehensive, interdisciplinary, quantitative characterization f fluvial-deltaic reservoir to allow realistic interwell and reservoir-scale models to be developed for improved oil-field development in similar reservoirs world-wide. Quantitative geological and petrophysical information on the Cretaceous Ferron Sandstone in east-central Utah was collected. Both new and existing data was integrated into a three-dimensional model of spatial variations in porosity, storativity, and tensorial rock permeability at a scale appropriate for inter-well to regional-scale reservoir simulation. Simulation results could improve reservoir management through proper infill and extension drilling strategies, reduction of economic risks, increased recovery from existing oil fields, and more reliable reserve calculations.

  2. Sequence Stratigraphy of the Desert System:A Case Study of the Lower Cretaceous in the Kuqa Basin in Xinjiang, Northwestern China

    Institute of Scientific and Technical Information of China (English)

    MEI Mingxiang; YU Bingsong; JIN Weiguang


    The Lower Cretaceous strata in the Kuqa Basin in Xinjiang are marked by a set of arid red beds. Several types of sedimentary facies can be identified in this set of arid red beds: mudstones of the plaza and intracontinental sebkha,aeolian sandstones, sandy conglomerates of the intermittent river, conglomerates of the pluvial fan, etc. These types of sedimentary facies constitute a typical desert system. Therefore, the Cretaceous strata in the Kuqa Basin provide a favorable condition for studies of sequence stratigraphic divisions of the desert system. With the rise and fall of the base level of the sedimentary basin, cyclicity is clearly revealed in stratigraphic records, which helps the identification of the third-order sequences. Based on the cyclicity in stratigraphic records, 5 third-order sequences can be found in the strata of the Early Cretaceous in the Kuqa Basin. These sequences comprise a second-order tectonic sequence. The primary feature of these third-order sequences is of an upward-fining sedimentary succession formed by a succession of"coarse sediments of the alluvial system-fine sediments of the lake system". The result of this study shows that aeolian sandstones are the best reservoirs of natural gas in the Cretaceous strata in the Kuqa Basin, and that the Kela-2 gas field is the first large gas field dominated by aeolian sandstone reservoirs in China.

  3. Optical Image Analysis Applied to Pore Network Quantification of Sandstones Under Experimental CO2 Injection (United States)

    Berrezueta, E.; González, L.; Ordóñez, B.; Luquot, L.; Quintana, L.; Gallastegui, G.; Martínez, R.; Olaya, P.; Breitner, D.


    This research aims to propose a protocol for pore network quantification in sandstones applying the Optical Image Analysis (OIA) procedure, which guarantees the measurement reproducibility and its reliability. Two geological formations of sandstone, located in Spain and potentially suitable for CO2 sequestration, were selected for this study: a) the Cretaceous Utrillas unit, at the base of the Cenozoic Duero Basin and b) a Triassic unit at the base of the Cenozoic Guadalquivir Basin. Sandstone samples were studied before and after the CO2 experimental injection using Optical and scanning electronic microscopy (SEM), while the quantification of petrographic changes was done with OIA. The first phase of the rersearch consisted on a detailed mineralogical and petrographic study of the sandstones (before and after CO2-injection), for which we observed thin sections. Later, the methodological and experimental processes of the investigation were focused on i) adjustment and calibration of OIA tools; ii) data acquisition protocol based on image capture with different polarization conditions (synchronized movement of polarizers), using 7 images of the same mineral scene (6 in crossed polarizer and 1 in parallel polarizer); and iii) automated identification and segmentation of pore in 2D mineral images, generating applications by executable macros. Finally, once the procedure protocols had been, the compiled data was interpreted through an automated approach and the qualitative petrography was carried out. The quantification of changes in the pore network through OIA (porosity increase ≈ 2.5%) has allowed corroborate the descriptions obtained by SEM and microscopic techniques, which consisted in an increase in the porosity when CO2 treatment occurs. Automated-image identification and quantification of minerals, pores and textures together with petrographic analysis can be applied to improve pore system characterization in sedimentary rocks. This research offers numerical

  4. Production of a Porosity Map by Kriging in Sandstone Reservoirs, Case Study from the Sava Depression

    Directory of Open Access Journals (Sweden)

    Tomislav Malvić


    Full Text Available Variogram analyses and usages of geostatistical interpolations have been standard analytical tools in Croatian geology in the last five years. Such analyses have especially been applied in the mapping of petroleum geological data. In this paper, spatial modelling of porosity data and, consequently, kriging mapping are described for a relatively large dataset obtained at an oil field located in the Croatian part of Pannonian basin (Sava depression. Analyzed datasets included porosity values measured in a sandstone reservoir of Pannonian age. The original dataset can be considered as a rare extensive porosity set available for Croatian hydrocarbon reservoirs. It made possible very reliable semivariogram modelling and kriging interpolation of porosity. The obtained results point out kriging as the most appropriate interpolation approach for porosity, but also for other geological data in sandstone reservoirs of Miocene age.

  5. Cretaceous shallow drilling, US Western Interior: Core research

    Energy Technology Data Exchange (ETDEWEB)

    Arthur, M.A.


    This project is a continuing multidisciplinary study of middle to Upper Cretaceous marine carbonate and clastic rocks in the Utah-Colorado-Kansas corridor of the old Cretaceous seaway that extended from the Gulf Coast to the Arctic during maximum Cretaceous transgressions. It is collaborative between in the US Geological Survey (W.E. Dean, P.I.) and University researchers led by The Pennsylvania State University(M.A. Arthur, P.I.) and funded by DOE and the USGS, in part. Research focusses on the Greenhom, Niobrara and lower Pierre Shale units and their equivalents, combining biostratigraphic/paleoecologic studies, inorganic, organic and stable isotopic geochemical studies, mineralogical investigations and high-resolution geophysical logging. This research requires unweathered samples and continuous smooth exposures'' in the form of cores from at least 4 relatively shallow reference holes (i.e. < 1000m) in transect from east to west across the basin. The major initial effort was recovery in Year 1 of the project of continuous cores from each site in the transect. This drilling provided samples and logs of strata ranging from pelagic sequences that contain organic-carbon-rich marine source rocks to nearshore coal-bearing units. This transect also will provide information on the extent of thermal maturation and migration of hydrocarbons in organic-carbon-rich strata along a burial gradient.

  6. Paleoceanographic events in cretaceous petroleum basins, offshore mid-Norway of SE Saskatchewan, Canada

    Energy Technology Data Exchange (ETDEWEB)

    Gradstein, F.M.; Saether, T.; Nystuen, J.P.; Backstrom, S.A. [Saga Petroleum A/S, Forus (Norway)


    During the Cretaceous period, the narrow, longitudinal seaways between Greenland and Norway received a large volume of fine-grained siliciclast sediments with intercalated gravity-flow sandstone wedges. The sedimentary succession may be subdivided into four broad units: (1) thin and mostly oxic, marly sediments, (2) dark, dysaerobic mudstones and minor sands, (3) thick mudstone facies with thin slope-apron turbidite sands, and (4) grayish laminated mudstones with local sands in the northern area. A widespread Barremian-Aptian hiatus may be linked to Atlantic rift-onset unconformities recognized offshore eastern Canada. Around the lower-upper Cretaceous boundary, watermass conditions changed from dysaerobic to oxic, an event also reported from central and western Europe.

  7. Impact Metamorphism of Sandstones at Amguid Crater, Algeria (United States)

    Sahoui, R.; Belhai, D.


    Amguid is a 450 m diameter sample crater; it is emplaced in Lower Devonian sandstones.We have carried out a petrographic study in order to investigate shock effects recorded in these sandstones and define shock stages in Amguid.

  8. Optimising geological storage of CO2 by development of multiple injection sites in regionally extensive storage sandstones (United States)

    Akhurst, Maxine; McDermott, Christopher; Williams, John; Mackay, Eric; Jin, Min; Tucker, Owain; Mallows, Tom; Hannis, Sarah; Pearce, Jonathan


    Carbon capture, transport and storage (CCS) is considered a key technology to provide secure, low-carbon energy supply and industrial processes to reduce the greenhouse gas emissions that contribute to the adverse effects of climatic change. Geological storage of carbon dioxide (CO2), captured during hydrocarbon production at the Sleipner Field, in strata beneath the Norwegian sector of the North Sea has been in operation since 1996. Projects to store CO2 captured at power plants in strata underlying the North Sea are currently in design. Storage of the CO2 is planned in depleted hydrocarbon fields or regionally extensive sandstones containing brine (saline aquifer sandstones). The vast majority of the UK potential storage resource is within brine-saturated sandstone formations. The sandstone formations are each hundreds to thousands of square kilometres in extent and underlie all sectors of the North Sea. The immense potential to store CO2 in these rocks can only be fully achieved by the operation of more than one injection site within each formation. Here we report an investigation into the operation of more than one injection site within a storage formation using a UK North Sea case study of the Captain Sandstone and the included Goldeneye Field, which is part of the mature hydrocarbon province offshore Scotland. Research by the CO2MultiStore project was targeted to increase understanding and confidence in the operation of two sites within the Captain Sandstone. Methods were implemented to reduce the effort and resources needed to characterise the sandstone, and increase understanding of its stability and performance during operation of more than one injection site. Generic learning was captured throughout the research relevant to the characterisation of extensive storage sandstones, management of the planned injection operations and monitoring of CO2 injection at two (or more) sites within any connected sandstone formation. The storage of CO2 can be optimised

  9. Fractures and stresses in Bone Spring sandstones

    Energy Technology Data Exchange (ETDEWEB)

    Lorenz, J.C.; Warpinski, N.R.; Sattler, A.R.; Northrop, D.A.


    This project is a collaboration between Sandia National Laboratories and Harvey E. Yates Company being conducted under the auspices of the Oil Recovery Technology Partnership. The project seeks to apply perspectives related to the effects of natural fractures, stress, and sedimentology to the simulation and production of low-permeability gas reservoirs to low-permeability oil reservoirs as typified by the Bone Spring sandstones of the Permian Basin, southeast New Mexico. This report presents the results and analysis obtained in 1989 from 233 ft of oriented core, comprehensive suite of logs, various in situ stress measurements, and detailed well tests conducted in conjunction with the drilling of two development wells. Natural fractures were observed in core and logs in the interbed carbonates, but there was no direct evidence of fractures in the sandstones. However, production tests of the sandstones indicated permeabilities and behavior typical of a dual porosity reservoir. A general northeast trend for the maximum principal horizontal stress was observed in an elastic strain recovery measurements and in strikes of drilling-induced fractures; this direction is subparallel to the principal fracture trend observed in the interbed carbonates. Many of the results presented are believed to be new information for the Bone Spring sandstones. 57 figs., 18 tabs.

  10. The Cretaceous System in China

    Institute of Scientific and Technical Information of China (English)


    This paper provides an outline of Cretaceous stratigraphy and paleogeography in China,which is based on rich data obtained from recent researches. Cretaceous deposits are widespread in China. Most strata are of nonmarine origin and marine sediments occur only in Tibet, western Tarim Basin of Xinjiang, Taiwan and limited localities of eastern Heilongjiang. All deposits are rich in fossils and well-constrained biostratigraphically. The stratigraphic successions of different regions are illustrated, and general stratigraphic division and correlation have been introduced. The marine deposits are described in the Tibetan Tethys, Kashi-Hotan Region of Xinjiang, eastern Heilongjiang,western Yunnan and Taiwan; the nonmarine deposits are outlined from northeast China, southeast China, southern interior China, southwest China, the Shaanxi-Gansu-Ningxia region, and northwestern China intermontane basins. The sedimentary facies and paleogeography are diversified.In Tibet the basin evolution is largely related to the subduction and collision of the Indian Plate against the Eurasian Continent, and shows a tectonic evolution in the Cretaceous. Foraminifera are a dominant biota in the Tibet Tethys. Nonmarine sediments include variegated and red beds, coal- or salt-bearing horizons, and volcanic rocks. These deposits contain diverse and abundant continental faunas and floras, as well as important coal and oil resources. The Cretaceous stratigraphy and paleogeography in China have presented a foundation for geological studies.

  11. Interaction of oil components and clay minerals in reservoir sandstones

    Energy Technology Data Exchange (ETDEWEB)

    Changchun Pan; Linping Yu; Guoying Sheng; Jiamo Fu [Chinese Academy of Sciences, State Key Lab. of Organic Geochemistry, Wushan, Guangzhou (China); Jianhui Feng; Yuming Tian [Chinese Academy of Sciences, State Key Lab. of Organic Geochemistry, Wushan, Guangzhou (China); Zhongyuan Oil Field Co., Puyang, Henan (China); Xiaoping Luo [Zhongyuan Oil Field Co., Puyang, Henan (China)


    The free oil (first Soxhlet extract) and adsorbed oil (Soxhlet extract after the removal of minerals) obtained from the clay minerals in the <2 {mu}m size fraction as separated from eight hydrocarbon reservoir sandstone samples, and oil inclusions obtained from the grains of seven of these eight samples were studied via GC, GC-MS and elemental analyses. The free oil is dominated by saturated hydrocarbons (61.4-87.5%) with a low content of resins and asphaltenes (6.0-22.0% in total) while the adsorbed oil is dominated by resins and asphaltenes (84.8-98.5% in total) with a low content of saturated hydrocarbons (0.6-9.5%). The inclusion oil is similar to the adsorbed oil in gross composition, but contains relatively more saturated hydrocarbons (16.87-31.88%) and less resins and asphaltenes (62.30-78.01% in total) as compared to the latter. Although the amounts of both free and adsorbed oils per gram of clay minerals varies substantially, the residual organic carbon content in the clay minerals of the eight samples, after the free oil extraction, is in a narrow range between 0.537% and 1.614%. From the decrease of the percentage of the extractable to the total of this residual organic matter of the clay minerals with burial depth it can be inferred that polymerization of the adsorbed polar components occurs with the increase of the reservoir temperature. The terpane and sterane compositions indicate that the oil adsorbed onto the clay surfaces appears to be more representative of the initial oil charging the reservoir than do the oil inclusions. This phenomenon could possibly demonstrate that the first oil charge preferentially interacts with the clay minerals occurring in the pores and as coatings around the grains. Although the variation of biomarker parameters between the free and adsorbed oils could be ascribed to the compositional changes of oil charges during the filling process and/or the differential maturation behaviors of these two types of oils after oil

  12. Provenance and U-Pb geochronology of the Upper Cretaceous El Chanate Group, northwest Sonora, Mexico, and its tectonic significance (United States)

    Jacques-Ayala, C.; Barth, A.P.; Wooden, J.L.; Jacobson, C.E.


    The Upper Cretaceous El Chanate Group, northwest Sonora, Mexico, is a 2.8km thick clastic sedimentary sequence deposited in a continental basin closely related to volcanic activity. It consists of three formations: the Pozo Duro (oldest), the Anita, and the Escalante (youngest). Petrographic study, conglomerate pebble counts, and U-Pb geochronology of detrital zircons were performed to determine the source and age of this sequence, and to interpret its tectonic setting. In the sandstones of all three formations, the most abundant grains are those of volcanic composition (Q38F22L 40, Q35F19L46, and Q 31F22L47, respectively). The Pozo Duro Formation includes well-rounded quartz-arenite clast conglomerates, whereas conglomerates of the two upper units have clasts predominantly of andesitic and rhyolitic composition. The most likely source for these sediments was the Jurassic volcanic arc exposed in northern Sonora and southern Arizona. Zircons from five sandstone samples define two main age groups, Proterozoic and Mesozoic. The first ranges mostly from 1000 to 1800Ma, which suggests the influence of a cratonic source. This zircon suite is interpreted to be recycled and derived from the same source area as the quartz-rich sandstone clasts in the basal part of the section. Mesozoic zircons range from Triassic to Late Cretaceous, which confirms the proposed Late Cretaceous age for the sequence, and also corroborates Jurassic felsic source rocks. Another possible source was the Alisitos volcanic arc, exposed along the western margin of the Baja California Peninsula. Of regional significance is the great similarity between the El Chanate Group and the McCoy Mountains Formation of southeastern California and southwestern Arizona. Both are Cretaceous, were deposited in continental environments, and have similar zircon-age patterns. Also, both exhibit intense deformation and locally display penetrative foliation. These features strongly suggest that both units underwent

  13. Origin and implications of fluid inclusions from filled fractures, Oriskany Sandstone, Allegheny Plateau, Pennsylvania

    Energy Technology Data Exchange (ETDEWEB)

    Basilone, T.; Anderson, T.; Burruss, R.C.


    Two cores from the Lower Devonian Oriskany Sandstone underlying the Allegheny Plateau in south-central Somerset County, Pennsylvania, contain fractures that may either be filled with epigenetic minerals or unfilled. The 1 Sipe core, taken from an unproductive well drilled on the crest of an anticlinal structure, is characterized by numerous discontinuous vertical fractures. The 1 Romesburg core, taken from a productive well drilled on the flank of an anticlinal structure, contains numerous fractures that lie parallel with bedding planes. The walls of these fractures consist of smooth slickensided surfaces. Quartz and ferroan-calcite crystals filling fractures contain numerous hydrocarbon-bearing fluid inclusions. The distribution of these fluid inclusions within most minerals allowed a determination to be made regarding the relative times of migration of fluid hydrocarbon phases in the subsurface with respect to the paragenetic sequence of mineralization events. Analysis of fluid inclusions indicates that fractures were opened at 22,000 ft (6700 m) and remained open throughout an extended period of uplift. Furthermore, inclusions contain hydrocarbon-rich fluids that are comparable to reservoir hydrocarbons in the nearby Shamrock field. This relationship implies that hydrocarbons that currently exist in reservoirs were conducted along fractures that were once open. Fractures crosscut diagenetic features, indicating that diagenesis, for the most part, preceded fracture events. Although they differ in origin and orientation, fractures characterizing Oriskany strata were healed by a consistent sequence of epigenetic minerals.

  14. Maps showing thermal maturity of Upper Cretaceous marine shales in the Bighorn Basin, Wyoming and Montana (United States)

    Finn, Thomas M.; Pawlewicz, Mark J.


    The Bighorn Basin is one of many structural and sedimentary basins that formed in the Rocky Mountain foreland during the Laramide orogeny, a period of crustal instability and compressional tectonics that began in latest Cretaceous time and ended in the Eocene. The basin is nearly 180 mi long, 100 mi wide, and encompasses about 10,400 mi2 in north-central Wyoming and south-central Montana. The basin is bounded on the northeast by the Pryor Mountains, on the east by the Bighorn Mountains, and on the south by the Owl Creek Mountains). The north boundary includes a zone of faulting and folding referred to as the Nye-Bowler lineament. The northwest and west margins are formed by the Beartooth Mountains and Absaroka Range, respectively. Important conventional oil and gas resources have been discovered and produced from reservoirs ranging in age from Cambrian through Tertiary. In addition, a potential unconventional basin-centered gas accumulation may be present in Cretaceous reservoirs in the deeper parts of the basin. It has been suggested by numerous authors that various Cretaceous marine shales are the principal source rock for these accumulations. Numerous studies of various Upper Cretaceous marine shales in the Rocky Mountain region have led to the general conclusion that these rocks have generated or are capable of generating oil and (or) gas. In recent years, advances in horizontal drilling and multistage fracture stimulation have resulted in increased exploration and completion of wells in Cretaceous marine shales in other Rocky Mountain Laramide basins that were previously thought of only as hydrocarbon source rocks. Important parameters controlling hydrocarbon production from these shale reservoirs include: reservoir thickness, amount and type of organic matter, and thermal maturity. The purpose of this report is to present maps and a cross section showing levels of thermal maturity, based on vitrinite reflectance (Ro), for selected Upper Cretaceous marine

  15. Main controlling factors for hydrocarbon reservoir formation and petroleum distribution in Cratonic Area of Tarim Basin

    Institute of Scientific and Technical Information of China (English)


    The Cratonic Area of the Tarim Basin is located in the central part of the basin, developing primarily with Cambrian marine source rocks and secondly Middle to Upper Ordovician marine and Carboniferous-Permian transitional facies source rocks. The source rocks were matured in the changeable period and space, forming multiple hydrocarbon generating centers during the periods. The Cratonic Area experienced multiple tectonic orogenies, forming several palaeouplifts. The matching condition between effective hydrocarbon generating centers and the palaeouplifts in various periods is the main control factor for the formation and distribution of hydrocarbon reservoirs. The palaeouplifts have experienced multiple hydrocarbon-filling phases, several periods of modifications and even breakdown. The palaeouplifts and the adjacent slopes around the effective hydrocarbon generating center compose the most favorable places for hydrocarbon accumulation. The hydrocarbon phase is related with the evolution of the hydrocarbon generating center. In the Tarim Basin's Cratonic Area, reservoirs were mostly formed during late Hercynian. The originally formed hydrocarbon reservoirs which are adjacent to source kitchens and in the good preservation condition are the most favorable prospecting targets. Hydrocarbon is richly accumulated under the regional caprock, surrounding the faulted trends, and over and below the unconformity surfaces. Reservoirs in the Carboniferous sandstone, Ordovician karstic weathered crust and carbonate rock inside the buried hill compose the main intervals for hydrocarbon accumulation. Carboniferous and Silurian sandstone pinchout reservoirs and carbonate lithologic reservoirs with rich fractures and pores are the main targets for further prospecting.

  16. Siderite (FeCO3)—the Hidden (but Primary) Player in Iron Diagenesis of Non-Marine Sandstones (United States)

    Loope, D.; Kettler, R. M.


    Siderite precipitates in reducing pore waters in which iron reduction exceeds sulfate reduction. Abundant siderite should be expected in non-marine strata in which a reductant was present. The Triassic Shinarump Member (Chinle Fm) and Cretaceous Dakota Fm are fluvial and contain siderite in outcrops of floodplain mudstones. Siderite is present in cores of Dakota channel sandstones. Rinded and jointed iron-oxide concretions, Wonderstone patterns, and rhombic, iron-oxide pseudomorphs are present in outcrops of these sandstones. Vascular plants growing on floodplains provided the reductant. Similar concretions, patterns, and pseudomorphs are present in outcropping eolian cross-strata of the Jurassic Navajo Sandstone and in fluvial sandstone of the Cambrian Umm Ishrin Fm. Bleached sandstones indicate reductant was present in both units during late diagenesis. Because Jurassic deserts and Cambrian river systems lacked vascular plants, extra-formational methane was the likely reductant. We interpret the various iron-oxide-cemented phenomena of the Shinarump, Dakota, Navajo, and Umm Ishrin as products of siderite oxidation that accompanied exhumation. In the Navajo, large concretions are enclosed in thick sheaths of iron-oxide cement. Through-going horizontal and vertical joints cut sheaths. Outside concretion sheaths, joints are unassociated with iron-oxide cements, but inside the sheaths, thick cement zones are present on both sides of (still-open) joints. Joints were conduits for oxidizing water entering the concretions. Redox gradients formed on both sides of joints and iron oxide accumulated as Fe+2 diffused from dissolving siderite toward joints and O2 diffused away from joints. Horizontal joints formed <100 m from the land surface. Iron-oxide accumulations on the horizontal joints and on the vertical joints that abut them (see figure) are evidence that siderite oxidation is ongoing and linked to exhumation.

  17. Tectonic Fractures in Tight Gas Sandstones of the Upper Triassic Xujiahe Formation in the Western Sichuan Basin,China

    Institute of Scientific and Technical Information of China (English)

    ZENG Lianbo; LI Yuegang


    The western Sichuan Basin,which is located at the front of the Longmen Mountains in the west of Sichuan Province,China,is a foreland basin formed in the Late Triassic.The Upper Triassic Xujiahe Formation is a tight gas sandstone reservoir with low porosity and ultra-low permeability,whose gas accumulation and production are controlled by well-developed fracture zones.There are mainly three types of fractures developed in the Upper Triassic tight gas sandstones,namely tectonic fractures,diagenetic fractures and overpressure-related fractures,of which high-angle tectonic fractures are the most important.The tectonic fractures can be classified into four sets,i.e.,N-S-,NE-,E-W-and NW-striking fractures.In addition,there are a number of approximately horizontal shear fractures in some of the medium-grained sandstones and grit stones nearby the thrusts or slip layers.Tectonic fractures were mainly formed at the end of the Triassic,the end of the Cretaceous and the end of the Neogene-Early Pleistocene.The development degree of tectonic fractures was controlled by lithology,thickness,structure,stress and fluid pressure.Overpressure makes not only the rock shear strength decrease,but also the stress state change from compression to tension.Thus,tensional fractures can be formed in fold-thrust belts.Tectonic fractures are mainly developed along the NE-and N-S-striking structural belts,and are the important storage space and the principal flow channels in the tight gas sandstone.The porosity of fractures here is 28.4% of the gross reservoir porosity,and the permeability of fractures being two or three grades higher than that of the matrix pores.Four sets of high-angle tectonic fractures and horizontal shear fractures formed a good network system and controlled the distribution and production of gas in the tight sandstones.

  18. Sedimentology and sequence stratigraphy of the Cretaceous Nanushuk, Seabee, and Tuluvak formations exposed on Umiat Mountain, north-central Alaska (United States)

    Houseknecht, David W.; Schenk, Christopher J.


    Upper Cretaceous strata of the upper part of the Nanushuk Formation, the Seabee Formation, and the lower part of the Tuluvak Formation are exposed along the Colville River on the east flank of Umiat Mountain in north-central Alaska. The Ninuluk sandstone, which is the uppermost unit of the Nanushuk Formation, displays a vertical succession of facies indicative of deposition in an upward-deepening estuarine through shoreface setting. A marine-flooding surface lies between the Ninuluk sandstone and organic-rich shale of the basal part of the Seabee Formation. The Ninuluk sandstone and the lower part of the Seabee Formation are interpreted as components of a transgressive-systems tract. The lowest, well-exposed strata in the Seabee Formation are a succession of shoreface sandstone beds in the middle of the formation. Integration of outcrop information and the Umiat No. 11 well log suggests that this sandstone succession rests on a sequence boundary and is capped by a marine-flooding surface. The sandstone succession is interpreted as a lowstand-systems tract. The upper part of the Seabee Formation includes a thick interval of organic-rich shale deposited in a dysaerobic offshore environment, and the gradational Seabee-Tuluvak contact is a coarsening-upward shale-to-sandstone succession deposited in a prodelta/delta-front environment. The observation that the upper part of the Seabee Formation correlates with seismic clinoforms suggests that dysaerobic conditions extended well up onto the prodelta slope during intervals of transgression and highstand. Correlation of the Umiat Mountain outcrop section with well logs and seismic data suggests that sequence boundaries and lowstand shoreface deposits may be common in the Seabee Formation and that wave action may have been important in transporting sand to the paleoshelf margin. These conclusions may contribute to an enhanced understanding of sand distribution in prospective lowstand turbidite deposits in the subsurface of

  19. Linkages Between Cretaceous Forearc and Retroarc Basin Development in Southern Tibet (United States)

    Orme, D. A.; Laskowski, A. K.


    Integrated provenance and subsidence analysis of forearc and retroarc foreland basin strata were used to reconstruct the evolution of the southern margin of Eurasia during the Early to Late Cretaceous. The Cretaceous-Eocene Xigaze forearc basin, preserved along ~600 km of the southern Lhasa terrane, formed between the Gangdese magmatic arc and accretionary complex as subduction of Neo-Tethyan oceanic lithosphere accommodated the northward motion and subsequent collision of the Indian plate. Petrographic similarities between Xigaze forearc basin strata and Cretaceous-Eocene sedimentary rocks of the northern Lhasa terrane, interpreted as a retroarc foreland basin, were previously interpreted to record N-S trending river systems connecting the retro- and forearc regions during Cretaceous time. New sandstone petrographic and U-Pb detrital zircon provenance analysis of Xigaze forearc basin strata support this hypothesis. Qualitative and statistical provenance analysis using cumulative distribution functions and Kolmogorov-Smirnov (K-S) tests show that the forearc basin was derived from either the same source region as or recycled from the foreland basin. Quartz-rich sandstones with abundant carbonate sedimentary lithic grains and rounded, cobble limestone clasts suggests a more distal source than the proximal Gangdese arc. Therefore, we interpret that the northern Lhasa terrane was a significant source of Xigaze forearc detritus and track spatial and temporal variability in the connection between the retro- and forearc basin systems during the Late Cretaceous. A tectonic subsidence curve for the Xigaze forearc basin shows a steep and "kinked" shape similar to other ancient and active forearc basins. Initial subsidence was likely driven by thermal relaxation of the forearc ophiolite after emplacement while additional periods of rapid subsidence likely result from periods of high flux magmatism in the Gangdese arc and changes in plate convergence rate. Comparison of the

  20. Hydrocarbon prospectivity in Western Greece

    Energy Technology Data Exchange (ETDEWEB)

    Maravelis, Angelos; Makrodimitras, George; Zelilidis, Avraam [Patras Univ. (Greece). Lab. of Sedimentology


    The geology of Western Greece is dominated by the most external zones of the Hellenide fold-and-thrust belt, namely the Pre-Apulian (or Paxoi) and Ionian zones. With Western Greece and Albania having undergone, in broad terms, similar geological histories, also the hydrocarbon potentials of both areas may be compared. Likewise, the hydrocarbon potential of Italy's Apulian Platform, adjoining in the westerly offshore, may serve as an analogue. Three basin types within Western Greece that deserve hydrocarbon exploration have been examined and are grouped, correlated to major tectonic features, namely foreland (Ionian thrusts' foreland basin), piggy-back (Ionian thrusts' back-arc basin) and strike-slip basins. Additionally, strike-slip basins are further subdivided into the basin north of the Borsh-Khardhiqit strike-slip fault and the Preveza basin, north of Cephalonia transfer fault. Their filling histories suggest the occurrence of Mesozoic carbonate plays and Oligocene/Miocene sandstone plays both for oil and gas.

  1. Experimental Analysis of Sandstone and Travertine

    Directory of Open Access Journals (Sweden)

    T. Doležel


    Full Text Available Sandstone and travertine are sedimentary rocks. The former is clastic, while the latter is sourced by chemical precipitation from hot springs. Their applications in civil engineering structures are mostly influenced by the ability to carry compression loading. A three-point bending experiment is usually used to determine material characteristics. However it does not correspond very well to applicatiosn in structures. For this reason we used a uniaxial compression test to obtain the modulus of elasticity and the stress-strain diagram. To obtain detailed information about the crystalline structure of sandstone and travertine a microscopic analysis wascarried out, using optical microscopy and an EDAX multichannel spectrometer for elementary microanalysis. 

  2. Mixed fluvial systems of Messak Sandstone, a deposit of Nubian lithofacies, southwestern Libya

    Energy Technology Data Exchange (ETDEWEB)

    Lorenz, J.C.


    The Messak Sandstone is a coarse to pebbly, tabular cross-bedded, Lower Cretaceous deposit of the widespread Nubian lithofacies. It was deposited at the northern edge of the Murzuq basin in southwestern Libya. Although the sedimentary record is predominantly one of braided fluvial systems, a common subfacies within the formation is interpreted to record the passage of straight-crested sand waves across laterally migrating point bars in sinuous rivers, similar to the pattern documented by Singh and Kumar on the modern Ganga and Yamuna Rivers. Because the sand waves were larger on the lower parts of the point bars, lateral migration created diagnostic thinning-upward, unidirectional cosets of tabular cross-beds as well as fining-upward, grain-size trends. Common, thick, interbedded claystones, deposited in associated paludal and lacustrine environments, and high variance in cross-bed dispersion patterns also suggest the local presence of sinuous fluvial systems within the overall braided regime. The Messak Sandstone contains some of the features that led Harms et al to propose an unconventional low-sinuosity fluvial environment for the Nubian lithofacies in Egypt, and the continuously high water levels of this model may explain channel-scale clay drapes and overturned cross-beds in the Messak. However, most of the Messak characteristics are incompatible with the low-sinuosity model, suggesting instead that the fluvial channels in the Murzuq basin alternated between braided and high-sinuosity patterns.

  3. Performance of Different Acids on Sandstone Formations

    Directory of Open Access Journals (Sweden)

    M. A. Zaman


    Full Text Available Stimulation of sandstone formations is a challenging task, which involves several chemicals and physical interactions of the acid with the formation. Some of these reactions may result in formation damage. Mud acid has been successfully used to stimulate sandstone reservoirs for a number of years. It is a mixture of hydrofluoric (HF and hydrochloric (HCl acids designed to dissolve clays and siliceous fines accumulated in the near-wellbore region. Matrix acidizing may also be used to increase formation permeability in undamaged wells. The change may be up to 50% to 100% with the mud acid. For any acidizing process, the selection of acid (Formulation and Concentration and the design (Pre-flush, Main Acid, After-flush is very important. Different researchers are using different combinations of acids with different concentrations to get the best results for acidization. Mainly the common practice is combination of Hydrochloric Acid – Hydrofluoric with Concentration (3% HF – 12% HCl. This paper presents the results of a laboratory investigation of Orthophosphoric acid instead of hydrochloric acid in one combination and the second combination is Fluoboric and formic acid and the third one is formic and hydrofluoric acid. The results are compared with the mud acid and the results calculated are porosity, permeability, and FESEM Analysis and Strength tests. All of these new combinations shows that these have the potential to be used as acidizing acids on sandstone formations.

  4. Characterization of hydrocarbon utilizing fungi from hydrocarbon ...

    African Journals Online (AJOL)

    Prof. Ogunji

    hydrocarbon polluted sediments and water .... ecosystem may result in selective increase or decrease in microbial population (Okpokwasili ... been implicated in degradation of hydrocarbons such as crude oil, polyaromatic hydrocarbons and.

  5. Lithological and Petrographic Analyses of Carbonates and Sandstones From the Southern Gulf of Mexico (United States)

    Garcia-Avendaño, A.; Urrutia-Fucugauchi, J.


    We present results of sedimentological and petrological studies of drill cores from the Bay of Campeche in the southern Gulf of Mexico. Based on reports on drill cores obtained from oil exploratory wells in the Cantarell Complex located 80 kilometres offshore in the Bay of Campeche and studies related to regional geology composite simplified stratigraphic columns for offshore Campeche region have been constructed up to depths of approximately 5000 m. The stratigraphic column is formed by a thick sediment sequence of Middle Jurassic age (evaporites, Callovian), Late Jurassic (terrigenous, calcareous clays and calcareous layers), Lower Cretaceous (carbonates), Upper Cretaceous-Paleogene (calcareous breccias), Paleogene-Neogene (terrigenous-carbonates intercalations) and Quaternary (terrigenous). The core samples studied come from wells in the Sihil and Akal fields in Cantarell. Analysis of reports on lithological descriptions indicates that these wells sample dolomitized sedimentary breccias from the Upper Cretaceous-Paleocene and fine-grained sandstones from the Late Jurassic Tithonian, respectively. Based on results of petrographic studies, the texture, cementing material and porosity of the units have been documented. The thin sections for carbonates were classified based on their texture according to Dunham (1962) for carbonate rocks, classified according to their components using the ternary diagrams of Folk (1974). Percentages refer to the data presented in tables, which were obtained by point-counting technique (with a total 250). Photomicrographs of scanning electron microscope (SEM) provide magnification for easy documentation of crystalline arrangements and description of micro-porous for different types of carbonates such as dolomite, in addition to the morphology of authigenic clays. Results of these studies and previous works in the area permit characterization of diagenetic processes of the carbonate sediments in the Campeche Bay, and provide

  6. Cretaceous sedimentation and tectonism in the southeastern Kaiparowits region, Utah (United States)

    Peterson, Fred


    Upper Cretaceous strata in the southeastern Kaiparowits region of south-central Utah consist of approximately 3,500 feet of interfingering sandstone, mudstone, shale, and coal in the Dakota Formation (oldest), Tropic Shale, Straight Cliffs Formation, and Wahweap Formation (youngest). The formations consist of several depositional facies that can be recognized by characteristic lithologies bedding structures, and fossils; these are the alluvial plain, deltaic plain, lagoonal-paludal, barrier sandstone, and offshore marine facies. The distribution of facies clearly defines the paleogeography of the region during several cycles of marine transgression and regression. The nonmarine beds were deposited on a broad alluvial coastal plain that was bordered on the west and southwest by highlands and on the east and northeast by the Western Interior seaway. The marine beds were deposited whenever the seaway advanced into or across the region. The Dakota Formation and the lower part of the Tropic Shale were deposited in nonmarine and marine environments, while the shoreline advanced generally westward across the region. The middle and upper part of the Tropic Shale and the Tibbet Canyon and Smoky Hollow Members of the Straight Cliffs Formation were deposited in marine and nonmarine environments when the seaway had reached its greatest areal extent and began a gradual northeastward withdrawal. An unconformity at the top of the Smoky Hollow represents a period of erosion and possibly nondeposition before deposition of the John Henry Member of the Straight Cliffs. The John Henry Member grades from nonmarine in the southwest to predominantly marine in the northeast, and was deposited during two relatively minor cycles of transgression and regression. The Drip Tank Member at the top of the Straight Cliffs Formation is a widespread sandstone unit deposited mainly in fluvial environments. Some of the beds in the northeastern part of the region were probably deposited in marine

  7. Hydrofacies In Sandstones. Evidence For Feedback Between Sandstone Lithofacies and Permeability Development (United States)

    Bloomfield, J. P.; Newell, A.; Moreau, M.

    In order to enhance our ability to develop effective numerical models of flow and con- taminant transport in the Permo-Triassic sandstone aquifer of the UK, relationships between lithofacies, rock mass characteristics (such as porosity and pore-throat size distribution), and permeability have been investigated through a series of case studies. Flow in the Permo-Triassic sandstones is primarily through the matrix. Permeability distribution is principally a function of the pore-throat size distribution and there is a relatively weak correlation with primary sedimentary lithofacies. It is observed that matrix permeability data broadly fall into two, discontinuous, sub-populations above and below about 1 mD. It is proposed that modification of primary sedimentary litho- facies by circulation of groundwater is the main control on the development of these two permeability sub-populations or hydrofacies. Identification of these two hydrofa- cies has significant implications for numerical modelling of the sandstones.

  8. Apparatus for hydrocarbon extraction (United States)

    Bohnert, George W.; Verhulst, Galen G.


    Systems and methods for hydrocarbon extraction from hydrocarbon-containing material. Such systems and methods relate to extracting hydrocarbon from hydrocarbon-containing material employing a non-aqueous extractant. Additionally, such systems and methods relate to recovering and reusing non-aqueous extractant employed for extracting hydrocarbon from hydrocarbon-containing material.

  9. Kinetic Modeling of Diagenesis of Eogene Lacustrine Sandstone Reservoirs in the Jianghan Basin, Southeastern China

    Institute of Scientific and Technical Information of China (English)

    倪师军; 卿海若; 唐建武; 周美夫; 李泽琴


    In the Tuoshi oilfield, located in the Cenozoic Jianghan Basin of southeastern China, there have been found hydrocarbon reservoirs hosted in lacustrine sandstones of the Eogene Xingouzui Formation. The main diagenetic features identified in these sandstones include the dissolution of detrital K-feldspar and albite grains, the precipitation of quartz as overgrowths and/or cements, and the precipitation and/or transformation of clay minerals. These diagenetic features were interpreted to have occurred in early, intermediate and late stages, based on the burial depth. The kinetics of fluid-mineral reactions and the concentrations of aqueous species at each stage of diagenesis were simulated numerically for these lacustrine sandstones, using a quasi-stationary state approximation that incorporates simultaneous chemical reactions in a time-space continuum. During the early diagenetic stage, pore fluid was weakly acidic, which resulted in dissolution of K-feldspar and albite and, therefore, led to the release of K + , Na + , Al3 + and SiO2(aq) into the diagenetic fluid. The increased K+ , Na + , Al3+ and SiO2(aq) concentrations in the diagenetic fluid caused the precipitation of quartz, kaolinite and illite. At the beginning of the intermediate diagenetic stage the concentration of H + was built up due to the decomposition of organic matter, which was responsible for further dissolution of K-feldspar and albite and precipitation of quartz, kaolinite, and illite. During the late diagenetic stage, the pore fluid was weakly alkaline, K-feldspar became stable and was precipitated with quartz and clay minerals.When the burial depth was greater than 3000 m, the pore fluids became supersaturated with respect to albite, but undersaturated with respect to quartz, resulting in the precipitation of albite and the dissolution of quartz. The diagenetic reactions forecasted in the numerical modeling closely matched the diagenetic features identified by petrographic examination, and

  10. Carbonate cementation-dissolution in deep-seated sandstones near the overpressure top in central Junggar Basin, Xinjiang, NW China

    Institute of Scientific and Technical Information of China (English)

    YANG Zhi; HE Sheng; WANG Furong; HE Zhiliang; WU Hengzhi; MENG Xianlong


    Fluid/rock interaction occurs frequently in the sandstones near the overpressure top in central Junggar Basin, and carbonate cementation-dissolution is related closely to the formation of secondary pores in the reservoir sandstones. From petrological, hydrochemical and fluid-inclusion studies of the deep-seated sandstones near the overpressure top in central Junggar Basin and the carbon and oxygen isotopic characteristics of carbonate cements in those sandstones, the following conclusions can be drawn: (1) Carbonates are the major cements. Two-stage cemen-tation was commonly developed, with late-stage ferroan carbonate cementation being dominant; several secondary porosity zones were developed vertically in the sandstones near the overpressure top, and there is a mutually com-pensatory relationship between the carbonate contents and the mean porosity; (2) the alkalescent formation-water chemical environments are in favor of carbonate precipitation; (3) there were two phases of thermal fluid activity which are related to the late-stage carbonate cementation-dissolution; (4) with the overpressure top as the boundary, carbonate cements in the sandstones have slightly negative δ13C and δ180 values, showing such a variation trend that the δ13C and δ18O values near the coal-bearing Jurassic strata are lighter, those in the overpressure top are heavier, and those at the upper part of the overpressure top are lighter, which is considered to be the result of kinetic isotope fractionation driven by episodically overpressured fluid flow; (5) carbonate cementation is closely associated with the decarboxylation of organic acids, and secondary porosity zones resultant from dissolution by organic acids and CO2 derived from Jurassic coal-beating strata, are the most important reservoir space of hydrocarbon, Studies of the mechanisms of carbonate cementation-dissolution and formation of secondary pores in the deep-seated sandstones near the overpressure top are of great

  11. Characterization of the Qishn sandstone reservoir, Masila Basin-Yemen, using an integrated petrophysical and seismic structural approach (United States)

    Lashin, Aref; Marta, Ebrahim Bin; Khamis, Mohamed


    This study presents an integrated petrophysical and seismic structural analysis that is carried out to evaluate the reservoir properties of Qishn sandstone as well as the entrapment style of the hydrocarbons at Sharyoof field, Sayun-Masila Basin that is located at the east central of Yemen. The reservoir rocks are dominated by clean porous and permeable sandstones zones usually intercalated with some clay stone interbeds. As identified from well logs, Qishn sandstone is classified into subunits (S1A, S1B, S1C and S2) with different reservoir characteristics and hydrocarbon potentiality. A number of qualitative and quantitative well logging analyses are used to characterize the different subunits of the Qishn reservoir and identify its hydrocarbon potentiality. Dia-porosity, M-N, Pickett, Buckles plots, petrophysical analogs and lateral distribution maps are used in the analysis. Shale volume, lithology, porosity, and fluid saturation are among the most important deduced parameters. The analysis revealed that S1A and S1C are the main hydrocarbon-bearing units. More specifically, S1A unit is the best, as it attains the most prolific hydrocarbon saturations (oil saturation "SH″ up to 65) and reservoir characteristics. An average petrophysical ranges of 4-21%, 16-23%, 11-19%, 0-65%, are detected for S1A unit, regarding shale volume, total and effective porosity, and hydrocarbon saturation, respectively. Meanwhile, S1B unit exhibits less reservoir characteristics (Vsh>30%, ϕEff<15% and SH< 15%). The lateral distribution maps revealed that most of the hydrocarbons (for S1A and S1C units) are indicated at the middle of the study area as NE-SW oriented closures. The analysis and interpretation of seismic data had clarified that the structure of study area is represented by a big middle horst bounded by a group of step-like normal faults at the extreme boundaries (faulted anticlinal-structure). In conclusion, the entrapment of the encountered hydrocarbon at Sharyoof oil

  12. Origin of gray-green sandstone in ore bed of sandstone type uranium deposit in north Ordos Basin

    Institute of Scientific and Technical Information of China (English)


    Dongsheng sandstone-type uranium deposit is located in the northern part of Ordos Basin, occurring in the transitional zones between gray-green and gray sandstones of Jurassic Zhiluo Formation. Sandstones in oxidized zone of the ore bed look gray-green, being of unique signature and different from one of ordinary inter-layered oxidation zone of sandstone-type uranium deposits. The character and origin of gray-green sandstones are systematically studied through their petrology, mineralogy and geochemistry. It is pointed out that this color of sandstones is originated from secondary oil-gas reduction processes after paleo-oxidation, being due to acicular-leaf chlorite covering surfaces of the sandstone grains. To find out the origin of gray-green sandstone and recognize paleo-oxidation zones in the ore bed are of not only theoretical significance for understanding metallogenesis of this kind of sandstone-type uranium deposit, but also very importantly practical significance for prospecting for similar kind of sandstone-type uranium deposit.

  13. Geology and recognition criteria for sandstone uranium deposits in mixed fluvial-shallow marine sedimentary sequences, South Texas. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Adams, S.S.; Smith, R.B.


    Uranium deposits in the South Texas Uranium Region are classical roll-type deposits that formed at the margin of tongues of altered sandstone by the encroachment of oxidizing, uraniferous solutions into reduced aquifers containing pyrite and, in a few cases, carbonaceous plant material. Many of the uranium deposits in South Texas are dissimilar from the roll fronts of the Wyoming basins. The host sands for many of the deposits contain essentially no carbonaceous plant material, only abundant disseminated pyrite. Many of the deposits do not occur at the margin of altered (ferric oxide-bearing) sandstone tongues but rather occur entirely within reduced, pyurite-bearing sandstone. The abundance of pyrite within the sands probably reflects the introduction of H/sub 2/S up along faults from hydrocarbon accumulations at depth. Such introductions before ore formation prepared the sands for roll-front development, whereas post-ore introductions produced re-reduction of portions of the altered tongue, leaving the deposit suspended in reduced sandstone. Evidence from three deposits suggests that ore formation was not accompanied by the introduction of significant amounts of H/sub 2/S.

  14. Geology and recognition criteria for sandstone uranium deposits in mixed fluvial-shallow marine sedimentary sequences, South Texas. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Adams, S.S.; Smith, R.B.


    Uranium deposits in the South Texas Uranium Region are classical roll-type deposits that formed at the margin of tongues of altered sandstone by the encroachment of oxidizing, uraniferous solutions into reduced aquifers containing pyrite and, in a few cases, carbonaceous plant material. Many of the uranium deposits in South Texas are dissimilar from the roll fronts of the Wyoming basins. The host sands for many of the deposits contain essentially no carbonaceous plant material, only abundant disseminated pyrite. Many of the deposits do not occur at the margin of altered (ferric oxide-bearing) sandstone tongues but rather occur entirely within reduced, pyurite-bearing sandstone. The abundance of pyrite within the sands probably reflects the introduction of H/sub 2/S up along faults from hydrocarbon accumulations at depth. Such introductions before ore formation prepared the sands for roll-front development, whereas post-ore introductions produced re-reduction of portions of the altered tongue, leaving the deposit suspended in reduced sandstone. Evidence from three deposits suggests that ore formation was not accompanied by the introduction of significant amounts of H/sub 2/S.

  15. Halomonas sulfidaeris-dominated microbial community inhabits a 1.8 km-deep subsurface Cambrian Sandstone reservoir. (United States)

    Dong, Yiran; Kumar, Charu Gupta; Chia, Nicholas; Kim, Pan-Jun; Miller, Philip A; Price, Nathan D; Cann, Isaac K O; Flynn, Theodore M; Sanford, Robert A; Krapac, Ivan G; Locke, Randall A; Hong, Pei-Ying; Tamaki, Hideyuki; Liu, Wen-Tso; Mackie, Roderick I; Hernandez, Alvaro G; Wright, Chris L; Mikel, Mark A; Walker, Jared L; Sivaguru, Mayandi; Fried, Glenn; Yannarell, Anthony C; Fouke, Bruce W


    A low-diversity microbial community, dominated by the γ-proteobacterium Halomonas sulfidaeris, was detected in samples of warm saline formation porewater collected from the Cambrian Mt. Simon Sandstone in the Illinois Basin of the North American Midcontinent (1.8 km/5872 ft burial depth, 50°C, pH 8, 181 bars pressure). These highly porous and permeable quartz arenite sandstones are directly analogous to reservoirs around the world targeted for large-scale hydrocarbon extraction, as well as subsurface gas and carbon storage. A new downhole low-contamination subsurface sampling probe was used to collect in situ formation water samples for microbial environmental metagenomic analyses. Multiple lines of evidence suggest that this H. sulfidaeris-dominated subsurface microbial community is indigenous and not derived from drilling mud microbial contamination. Data to support this includes V1-V3 pyrosequencing of formation water and drilling mud, as well as comparison with previously published microbial analyses of drilling muds in other sites. Metabolic pathway reconstruction, constrained by the geology, geochemistry and present-day environmental conditions of the Mt. Simon Sandstone, implies that H. sulfidaeris-dominated subsurface microbial community may utilize iron and nitrogen metabolisms and extensively recycle indigenous nutrients and substrates. The presence of aromatic compound metabolic pathways suggests this microbial community can readily adapt to and survive subsurface hydrocarbon migration.

  16. Late Cretaceous stratigraphy of the Upper Magdalena Basin in the Payandé-Chaparral segment (western Girardot Sub-Basin), Colombia (United States)

    Barrio, C. A.; Coffield, D. Q.


    The Cretaceous section on the western margin of the Girardot Sub-Basin, Upper Magdalena Valley, is composed of the Lower Sandstone (Hauterivian-Barremian?), Tetuán Limestone (pre-Aptian?), and Bambuca Shale (pre-Aptian?), and the following formations: Caballos (Aptian-Albian), Villeta (Albian-Campanian), Monserrate (Campanian-Maastrichtian), and Guaduas (Maastrichtian-Paleocene). The Lower Sandstone is composed of quartz arenites with abundant calcareous cement; the Tetuúan Limestone is a succession of fossiliferous limestones and calcareous shales; the the Bambuca Shale is composed of black shales that grade upward to micritic limestones and calcarenites. The Caballos Formation comprises three members: a lower member of quartz arenites, a middle member of black shales and limestones, and an upper member of crossbedded, coarsening-upward quartz arenites. The Villeta Formation is a sequence of shales intercalated with micritic limestones and calcarenites. Two levels of chert (Upper and Lower Chert) are differentiated within the Villeta Formation throughout the study area, with a sandstone unit (El Cobre Sandstone) to the north. The Monserrate Formation is composed of quartz arenites, with abundant crossbedding, and locally of limestone breccias and coarse-grained fossiliferous packstones. The Guaduas Formation is a monotonous succession of red shales and lithic sandstones. Our data suggest three major transgressive-regressive cycles in the Girardot Sub-Basin. The first cycle (Hauterivian?-lower Aptian) is represented by the Lower Sandstone-Tetuán-Bambuca-lower Caballos succession, the second cycle (Aptian-Albian) by the middle-upper Caballos members, and the third cycle (Albian-Paleocene) by the lower Villeta-Monserrate-Guaduas succession. Previous studies proposed a eustatic control during deposition of the Upper Cretaceous in the Upper Magdalena Valley. The lowermost transgressive-regressive cycle was not previously differentiated in the study area, and this

  17. Analysis of Radiation Exposure for Naval Personnel at Operation SANDSTONE. (United States)


    Operation SANDSTONE Dose Reconstruction Methodology I I 2-1 Enewetak Atoll Anchorage Areas 14 2-2 Destroyer Patrol Sector Chart for Operation SANDSTONE 18...2-3 Average Free-Field Radiation Intensity for Southern and Northern Anchorage Areas - Enewetak Atoll 24 2-4 Average Free-Field Radiation Intensity...Operation SANDSTONE was the second nuclear test series held in the Marshall 0 Islands. It consisted of three nuclear weapon tests at Enewetak * Atoll in

  18. Detrital Zircon Geochronology of Cretaceous and Paleogene Strata Across the South-Central Alaskan Convergent Margin (United States)

    Bradley, Dwight; Haeussler, Peter; O'Sullivan, Paul; Friedman, Rich; Till, Alison; Bradley, Dan; Trop, Jeff


    Ages of detrital zircons are reported from ten samples of Lower Cretaceous to Paleogene metasandstones and sandstones from the Chugach Mountains, Talkeetna Mountains, and western Alaska Range of south-central Alaska. Zircon ages are also reported from three igneous clasts from two conglomerates. The results bear on the regional geology, stratigraphy, tectonics, and mineral resource potential of the southern Alaska convergent margin. Chugach Mountains - The first detrital zircon data are reported here from the two main components of the Chugach accretionary complex - the inboard McHugh Complex and the outboard Valdez Group. Detrital zircons from sandstone and two conglomerate clasts of diorite were dated from the McHugh Complex near Anchorage. This now stands as the youngest known part of the McHugh Complex, with an inferred Turonian (Late Cretaceous) depositional age no older than 91-93 Ma. The zircon population has probability density peaks at 93 and 104 Ma and a smattering of Early Cretaceous and Jurassic grains, with nothing older than 191 Ma. The two diorite clasts yielded Jurassic U-Pb zircon ages of 179 and 181 Ma. Together, these findings suggest a Mesozoic arc as primary zircon source, the closest and most likely candidate being the Wrangellia composite terrane. The detrital zircon sample from the Valdez Group contains zircons as young as 69 and 77 Ma, consistent with the previously assigned Maastrichtian to Campanian (Late Cretaceous) depositional age. The zircon population has peaks at 78, 91, 148, and 163 Ma, minor peaks at 129, 177, 330, and 352 Ma, and no concordant zircons older than Devonian. A granite clast from a Valdez Group conglomerate yielded a Triassic U-Pb zircon age of 221 Ma. Like the McHugh Complex, the Valdez Group appears to have been derived almost entirely from Mesozoic arc sources, but a few Precambrian zircons are also present. Talkeetna Mountains - Detrital zircons ages were obtained from southernmost metasedimentary rocks of the

  19. Structure and depositional processes of a gravelly tsunami deposit in a shallow marine setting: Lower Cretaceous Miyako Group, Japan (United States)

    Fujino, S.; Masuda, F.; Tagomori, S.; Matsumoto, D.


    This study reports a newly discovered gravelly tsunami deposit from the Lower Cretaceous Miyako Group, Japan. The deposit was formed in an open shallow marine setting. The event deposit erosionally overlies shoreface deposits and shows marked lateral facies change. At the basin margin, the deposit is composed mainly of amalgamated HCS sandstones with liquefaction structures, overlain by finer sediments that contain many plant fragments or micas. Conglomerates accompanying the HCS sandstones contain molluscan fossils and many coral clasts. In the basin center, the event deposit is made up mainly of conglomerates and lenticular sandstone beds, and passes upwards into alternating sandstones and siltstones. A condensed organic debris layer is intercalated within the alternating section. Conglomerates contain abundant beach gravel, and also contain beachrock, coral blocks, and boulders. Bivalve fossils are well preserved despite their occurrence in grain-supported conglomerates. The event deposit is divided into sub-layers bounded by internal scours that are wavy and intersect. Each sub-layer consists of a conglomerate grading into a sandstone layer. Imbrications just above the scours in sub-layers show seawards paleocurrents; however, imbrications just beneath the sandstone horizons in the same sub-layers feature landward paleocurrents. Respective sub-layers in the tsunami deposit were formed by substrate erosion due to backwash flow, gravel deposition, reworking by flood flow, and sand deposition during the stagnant water period. The overall upward-fining trend reflects decline of the tsunami event. Development of the gravelly deposit in the central part of the basin and lateral facies change may be attributed to hydrodynamic response of the tsunami pulse to local bathymetry and geography.

  20. Sedimentology and Stratigraphic architecture of the early Cretaceous Alpian-Aptian succession of the Kiklah Formation, Jabal Nafusah, NW Libya (United States)

    Hlal, Osama


    Kiklah Formation is presents on the Jabal Nafusah escarpment for almost 400 km from the Tunisian border to the east of Gharyan. Kiklah Formation overlies the Early Cretaceous, Jurassic and Triassic sediments of Jabal Nafusah with marked unconformity. On the other hand, it is unconformably overlain by the Sidi as Sid Formation. This contact with overlying units is angular unconformity as it is evident only in the central Gharyan area. The Kiklah Formation consists mainly of continental deposits such as conglomeratic sandstone, pebble sandstone, and mudstone with minor lacustrine interbeds of reddish yellow to greenish claystone. In addition, these rocks were formed by a braided river system carrying heavy sediment loads, with frequent shifting of the principal channels. SEM studies show pitting and breakage features on the sand grains which are diagnostic of Fluvial depositional environment. In the Nafusah region the Kiklah Formation varies in thickness westward from absence near Gharyan to over 610 m in Tunisian subsurface.

  1. Wilcox sandstone reservoirs in the deep subsurface along the Texas Gulf Coast: their potential for production of geopressured geothermal energy. Report of Investigations No. 117

    Energy Technology Data Exchange (ETDEWEB)

    Debout, D.G.; Weise, B.R.; Gregory, A.R.; Edwards, M.B.


    Regional studies of the lower Eocene Wilcox Group in Texas were conducted to assess the potential for producing heat energy and solution methane from geopressured fluids in the deep-subsurface growth-faulted zone. However, in addition to assembling the necessary data for the geopressured geothermal project, this study has provided regional information of significance to exploration for other resources such as lignite, uranium, oil, and gas. Because the focus of this study was on the geopressured section, emphasis was placed on correlating and mapping those sandstones and shales occurring deeper than about 10,000 ft. The Wilcox and Midway Groups comprise the oldest thick sandstone/shale sequence of the Tertiary of the Gulf Coast. The Wilcox crops out in a band 10 to 20 mi wide located 100 to 200 mi inland from the present-day coastline. The Wilcox sandstones and shales in the outcrop and updip shallow subsurface were deposited primarily in fluvial environments; downdip in the deep subsurface, on the other hand, the Wilcox sediments were deposited in large deltaic systems, some of which were reworked into barrier-bar and strandplain systems. Growth faults developed within the deltaic systems, where they prograded basinward beyond the older, stable Lower Cretaceous shelf margin onto the less stable basinal muds. Continued displacement along these faults during burial resulted in: (1) entrapment of pore fluids within isolated sandstone and shale sequences, and (2) buildup of pore pressure greater than hydrostatic pressure and development of geopressure.

  2. Tar sandstones in the Parana Basin: a study of the occurrences in the Anhembi Structural High; Arenitos asfalticos na Bacia do Parana: estudo das ocorrencias no Alto Estrutural de Anhembi

    Energy Technology Data Exchange (ETDEWEB)

    Araujo, Carlos Cesar de [PETROBRAS S.A., Rio de Janeiro, RJ (Brazil). Area de Negocio Internacional], E-mail:; Yamamoto, Jorge Kazuo; Rostirolla, Sidnei Pires


    There are tar accumulations in Early Triassic sandstones along the eastern margin of the Parana Basin. The aim of this research work is to explain the tar sandstone occurrences in the Anhembi High. The Anhembi High, where permian mudstones outcrop in a Triassic sandstone area, is a Jurassic-Cretaceous structure related to the reactivation of pre-existing basement faults. Tar was derived from Permian source rocks that matured along the basic sills of the continental flood basalt cover of Serra Geral Formation. This paper examines the habitat of tar accumulation and integrates fieldwork with morpho structural data, digital elevation model, gravity and airborne magnetic data and remote sensing imagery. The interpretation of the structural framework is based primarily on the morpho structural analysis, the distribution of gravity and magnetic anomalies and on a structural field survey. The Anhembi High consists of three blocks with a N50W-trending major axis. Tar sandstone outcrops occur around the Anhembi structure, on its low-lying block and are restricted to the lower Piramboia Formation. The morpho structural interpretation suggests the occurrence of tar sandstones at intermediate positions, between the structural highs and lows. The most likely explanation for these tar accumulations relates oil maturation and migration to the intrusion of Early Cretaceous Serra Geral sills into the Late Permian black shales of the Irati Formation, and subsequent migration along faults and dyke walls into eolian sandstone reservoirs of the Triassic Piramboia Formation. Not only did the basic dykes locally facilitate migration, but there were also places where they constituted barriers to lateral migration. Furthermore, the interdune and fluvial facies of the Piramboia Formation formed local seals and barriers to vertical migration.

  3. Submarine fan sedimentation at a convergent margin: the cretaceous mangapokia formation, New Zealand (United States)

    Barnes, Philip M.


    The middle Cretaceous Mangapokia Formation (Pahaoa Group) near Te Awaiti, southeast North Island, New Zealand, consists of indurated, poorly fossiliferous, alternating sandstone and argillite, minor conglomerate, grit, pebbly-sandstone, and pebbly-mudstone (terrigenous sedimentary assemblage), and minor basalt, coloured argillite, chert, and micritic limestone (ocean-floor assemblage). Seven lithofacies are distinguished in the sedimentary assemblage on the basis of lithology, bed thickness and geometry, sand/mud ratio, grain size and internal sedimentary features. Facies 1 (10-15% of total exposure), which includes all sediments coarser than sand grade, comprises seven subfacies as follows: lenticular and erosive beds of coarse-grained (Subfacies 1Ai), medium-grained (Subfacies 1Aii) and fine-grained (Subfacies 1Aiii) predominantly clast-supported conglomerate, grit (Subfacies 1Aiv) and pebbly-sandstone (Subfacies 1Av) displaying numerous types of graded bedding and sedimentary structures, were all deposited predominantly from high-concentration turbidity currents or bed-load inertia flows. Minor chaotic sand or mud matrix-supported conglomerate lenses (Subfacies 1Bi), and beds which show clear evidence of post-depositional remobilisation (Subfacies 1Bii), represent debris flow deposits. Thick lenses of sandstone and minor argillite interbeds (Facies 2) were deposited from large-volume inertia flows, possibly grainflows. Facies 3, the most common lithofacies, consists of laterally more extensive, medium thickness, graded beds of alternating sandstone and argillite with rare Bouma sequences. These deposits are proximal turbidites which accumulated in environments more distal than Facies 1 and 2. Thin-bedded (Facies 4) and very thin-bedded (Facies 5) alternating sandstone and argillite, and argillite-dominated sequences with minor interbedded sandstone (Facies 6) were deposited in interchannel depressions, on channel levees, or in areas distant from high

  4. Biodegradation of phenols in a sandstone aquifer under aerobic conditions and mixed nitrate and iron reducing conditions

    DEFF Research Database (Denmark)

    Broholm, Mette; Arvin, Erik


    in the groundwater. The potential for biodegradation of the phenols in the sandstone aquifer at the site has been investigated in laboratory microcosms under aerobic (oxygen amended) and mixed nitrate and iron reducing (nitrate enriched and unamended) anaerobic conditions, at a range of concentrations (low: similar...... to 5 mg 1(-1): high: similar to 60 mg 1(-1), and very high: similar to 600 mg 1(-1)) and in the presence of other organic coal-tar compounds (mono- and polyaromatic hydrocarbons (BTEXs and PAHs) and heterocyclic compounds (NSOs)) and ammonia liquor. Sandstone cores and groundwater for the microcosms...... biodegradation of phenol, cresols, 3,4-xylenol and 3,5-xylenol was observed after short lag-phases in the anaerobic microcosms. 2,5-xylenol was partially degraded after a longer lag-phase and 2,6-xylenol persisted throughout the 3 month long experiments. The maximum rates of total phenols degradation...

  5. Stratigraphy, foraminiferal assemblages and paleoenvironments in the Late Cretaceous of the Upper Magdalena Valley, Colombia (part I) (United States)

    Vergara, Luis S.


    The present work focuses on the Cretaceous record (Middle Albian-Maastrichtian) of the Upper Magdalena Valley (UMV), with a scope that covers facies and biofacies. The nomenclatural scheme previously stated for the Girardot-Guataqui area is here extended and proposed for all the basin, the following fomational units being characterized in detail. The Hondita Formation (Middle Albian-late Turonian), placed on top of the Caballos Formation, is separated from the Lomagorda Formation (late Turonian-early Santonian) by a chert interval within a succession of predominantly dark shales deposited in outer shelf environments. The Olini Group (early Santonian-late Campanian) presents two conspicuous chert units (Lidita Inferior and Superior) overlain by the Nivel de Lutitas y Arenas (early Maastrichtian). The sandstones of La Tabla and finally the mudstones of the Seca Formation (Maastrichtian) represent diverse littoral environments of the end of the Cretaceous. In the UMV, the Cretaceous system attains approximately 1350 m of thickness. Within the paleogeographic scenario, the drowning of the basin and of the adjacent Central Cordillera during most of the Late Cretaceous enabled upwelling currents and the development of widespread pelagic sediments. These sediments graded to shallower water deposits towards the south of the basin. In the Upper Cretaceous, four sequences of second order can be identified. The longer cycle begins at the base of the Hondita Formation and exhibits the maximum flooding in the Cenomanian condensed section of this unit. Following this cycle, three successive sudden sea level drops mark the boundaries of complete sequences, each comprising well developed lowstand, transgressive and highstand system tracts. After the last cycle was completed, the basin was uplifted and rocks of the Seca Formation were cannibalized by fluvial processes during the Tertiary. An angular unconformity that truncates this unit represents the uppermost sequence boundary of

  6. Cretaceous shallow drilling, U.S. Western Interior: Core research. Final technical report

    Energy Technology Data Exchange (ETDEWEB)

    Arthur, M.A.


    The primary objective of the project is to construct a subsurface transect of Cretaceous strata that were deposited in the Kansas-Colorado-Utah corridor, going from marine sequences that contain organic-carbon-rich hydrocarbon source rocks in Kansas and eastern Colorado to nearshore coal-bearing units in western Colorado and Utah. The drilling transect will provide continuous, unweathered samples for inorganic, organic, and isotopic geochemical studies and mineralogical investigations to determine the characteristics of hydrocarbon source rocks. This transect also will provide information on the extent of thermal maturation and migration of hydrocarbons in organic-carbon-rich strata along a burial gradient. In addition, the eastern Colorado hole will provide characteristics of an important fractured reservoir (the Pierre Shale) in the Florence oil field, the oldest continuously producing field in the United States (>100 years; 600 wells; >14 Mbbls).

  7. Stratigraphic and Petrological Constraints of Cretaceous Subduction Initiation and Arc-Continent Collision in the Northern Andes (United States)

    Leon, S.; Cardona, A.; Mejia, D.; Parra, M.


    Middle to Late-Cretaceous orogenic events in the northern Andes have been commonly reconstructed from the analysis of inland basins or the integration of regional scale thermochronological, geochronological and geochemical datasets from the accreted blocks. In contrast, limited studies have been developed on the stratigraphic and deformational record of magmatic and sedimentary sequences exposed near the suture zones. New field and petrologic data are used to characterize an ophiolite type sequence that outcrops in the western flank from the northwestern segment of the Central Cordillera of Colombia. Stratigraphic analysis indicate the existence of Albian-Aptian deep marine pelitic sequence interbedded with minor chert and thin quartz sandstone beds that apparently change to a volcanic dominate stratigraphy. Deformed ophiolite-like mafic and ultramafic plutonic rocks and isolated pillow lavas are also exposed to the east in fault contact with the pelitic sequence. The pelitic and interlayered volcanic rocks represent the growth of an extensional Early-Cretaceous basin that followed a Late-Jurassic magmatic quiescence in the Northern Andes. The volcano-sedimentary record is probably related to the growth of a fore-arc basin in a new subduction zone that extends until the Late Cretaceous. The deformation and obduction of the ophiolitic association and the fore-arc basin were probably triggered by the Late Cretaceous collision with an allocthonous plateau-arc associated to the migration of the Caribbean plate.

  8. Mechanism of Solid Bitumen in Silurian Sandstones of Tarim Basin

    Institute of Scientific and Technical Information of China (English)

    Zhang Jinglian; Zhu Bingquan


    @@ There are a large amount of solid bitumen within Silurian sandstones in Tabei, Tazhong, Kalpin uprifts of the Tarim Basin. Petroleum geochemists are interested in the super giant fossil oil pool. Unfortunately,some key questions have not been solved, such as: what generated the bitumen? When did the bitumen generate and when did the bitumen accumulated in the sandstones?

  9. Brittle and compaction creep in porous sandstone (United States)

    Heap, Michael; Brantut, Nicolas; Baud, Patrick; Meredith, Philip


    Strain localisation in the Earth's crust occurs at all scales, from the fracture of grains at the microscale to crustal-scale faulting. Over the last fifty years, laboratory rock deformation studies have exposed the variety of deformation mechanisms and failure modes of rock. Broadly speaking, rock failure can be described as either dilatant (brittle) or compactive. While dilatant failure in porous sandstones is manifest as shear fracturing, their failure in the compactant regime can be characterised by either distributed cataclastic flow or the formation of localised compaction bands. To better understand the time-dependency of strain localisation (shear fracturing and compaction band growth), we performed triaxial deformation experiments on water-saturated Bleurswiller sandstone (porosity = 24%) under a constant stress (creep) in the dilatant and compactive regimes, with particular focus on time-dependent compaction band formation in the compactive regime. Our experiments show that inelastic strain accumulates at a constant stress in the brittle and compactive regimes leading to the development of shear fractures and compaction bands, respectively. While creep in the dilatant regime is characterised by an increase in porosity and, ultimately, an acceleration in axial strain to shear failure (as observed in previous studies), compaction creep is characterised by a reduction in porosity and a gradual deceleration in axial strain. The overall deceleration in axial strain, AE activity, and porosity change during creep compaction is punctuated by excursions interpreted as the formation of compaction bands. The growth rate of compaction bands formed during creep is lower as the applied differential stress, and hence background creep strain rate, is decreased, although the inelastic strain required for a compaction band remains constant over strain rates spanning several orders of magnitude. We find that, despite the large differences in strain rate and growth rate

  10. Subsurface sandstone mapping by combination of GPR and ERT method

    Institute of Scientific and Technical Information of China (English)

    YOU Zhixin


    It is important to know the shape and distribution of sandstone bodies in the subsurface when forma-tion and migration of a dune model are determined.The information plays a significant role in identification of the continental oil and gas accumulation.In this study,the combination of ground penetrating radar (GPR) and electrical resistivity tomography method (ERT)is used in mapping the distribution of sandstone bodies in Yanchang Formation.Six GPR profiles and seven ERT profiles are used to analysis.GPR data show clear re-flections from the top interface of sandstones.ERT data show a continuous high resistivity anomaly correspon-ding to the sandstone body.Combined the reconstructed 3D images by GPR and ERT,the spatial distribution of sandstone bodies is described.

  11. Petroacoustic Modelling of Heterolithic Sandstone Reservoirs: A Novel Approach to Gassmann Modelling Incorporating Sedimentological Constraints and NMR Porosity data (United States)

    Matthews, S.; Lovell, M.; Davies, S. J.; Pritchard, T.; Sirju, C.; Abdelkarim, A.


    Heterolithic or 'shaly' sandstone reservoirs constitute a significant proportion of hydrocarbon resources. Petroacoustic models (a combination of petrophysics and rock physics) enhance the ability to extract reservoir properties from seismic data, providing a connection between seismic and fine-scale rock properties. By incorporating sedimentological observations these models can be better constrained and improved. Petroacoustic modelling is complicated by the unpredictable effects of clay minerals and clay-sized particles on geophysical properties. Such effects are responsible for erroneous results when models developed for "clean" reservoirs - such as Gassmann's equation (Gassmann, 1951) - are applied to heterolithic sandstone reservoirs. Gassmann's equation is arguably the most popular petroacoustic modelling technique in the hydrocarbon industry and is used to model elastic effects of changing reservoir fluid saturations. Successful implementation of Gassmann's equation requires well-constrained drained rock frame properties, which in heterolithic sandstones are heavily influenced by reservoir sedimentology, particularly clay distribution. The prevalent approach to categorising clay distribution is based on the Thomas - Stieber model (Thomas & Stieber, 1975), this approach is inconsistent with current understanding of 'shaly sand' sedimentology and omits properties such as sorting and grain size. The novel approach presented here demonstrates that characterising reservoir sedimentology constitutes an important modelling phase. As well as incorporating sedimentological constraints, this novel approach also aims to improve drained frame moduli estimates through more careful consideration of Gassmann's model assumptions and limitations. A key assumption of Gassmann's equation is a pore space in total communication with movable fluids. This assumption is often violated by conventional applications in heterolithic sandstone reservoirs where effective porosity, which

  12. Power-law Scaling of Fracture Aperture Sizes in Otherwise-Undeformed Foreland Basin Sandstone: An Example From the Cozzette Sandstone, Piceance Basin, Colorado (United States)

    Hooker, J. N.; Gale, J. F.; Laubach, S. E.; Gomez, L. A.; Marrett, R.; Reed, R. M.


    Power-law variation of aperture size with cumulative frequency has been documented in vein arrays, but such patterns have not been conclusively demonstrated from open or incompletely mineralized opening-mode fractures (joints) in otherwise-undeformed sedimentary rocks. We used subhorizontal core from the nearly flat- lying Cretaceous Cozzette Sandstone, Piceance Basin, Colorado, to document fracture aperture sizes over five orders of magnitude. We measured microfractures (0.0004-0.1164 mm in aperture) along a 276-mm-long scanline using scanning electron microscope-based cathodoluminescence; we measured macrofractures (0.5- 2.15 mm in aperture) in 35 m of approximately horizontal core cut normal to fracture strike. Microfractures are typically filled with quartz. Macrofractures are mostly open and resemble non-mineralized joints, except for thin veneers of quartz cement lining their walls. Micro- and macrofractures share both a common orientation and the same timing with respect to diagenetic sequence, only differing in size and the degree to which they are filled with quartz cement. Power-law scaling equations were derived by fitting trendlines to aperture vs. cumulative frequency data for the microfractures. These equations successfully predicted the cumulative frequencies of the macrofractures, accurate to within a factor of four in each test and within a factor of two in 75 percent of tests. Our results show that tectonic deformation is not prerequisite for power-law scaling of fractures, but instead suggest that scaling emerges from fracture interaction during propagation.

  13. Reconstructing a mid-Cretaceous landscape from paleosols in western Canada (United States)

    Ufnar, David F.; Gonzalez, Luis A.; Ludvigson, Greg A.; Brenner, Richard L.; Witzke, B.J.; Leckie, D.


    The Albian Stage of the mid-Cretaceous was a time of equable climate conditions with high sea levels and broad shallow epeiric seas that may have had a moderating affect on continental climates. A Late Albian landscape surface that developed during a regression and subsequent sea-level rise in the Western Canada Foreland Basin is reconstructed on the basis of correlation of paleosols penetrated by cores through the Paddy Member of the Peace River Formation. Reconstruction of this landscape refines chronostratigraphic relationships and will benefit future paleoclimatological studies milizing continental sphaerosiderite proxy records. The paleosols developed in estuarine sandstones and mudstones, and they exhibit evidence of a polygenetic history. Upon initial exposure and pedogenesis, the Paddy Member developed deeply weathered, well-drained cumulative soil profiles. Later stages of pedogenesis were characterized by hydromorphic soil conditions. The stages of soil development interpreted for the Paddy Member correlate with inferred stages of pedogenic development in time-equivalent formations located both basinward and downslope (upper Viking Formation), and landward and upslope (Boulder Creek Formation). On the basis of the genetic similarity among paleosols in these three correlative formations, the paleosols are interpreted as having formed along a single, continuous landscape surface. Results of this study indicate that the catena concept of pedogenesis along sloping landscapes is applicable to ancient successions. Sphaerosiderites in the Paddy Mem ber paleosols are used to provide proxy values for meteoric ??18O values at 52?? N paleolatitude in the Cretaceous Western Interior Basin. The meteoric ??18O values are used to refine existing interpretations about the mid-Cretaceous paleolatitudinal gradient in meteoric ?? 18O values, and the mid-Cretaceous hydrologic cycle. Copyright ?? 2005, SEPM (Society for Sedimentary Geology).

  14. Geochemical evaluation of upper cretaceous fruitland formation coals, San Juan Basin, New Mexico and Colorado (United States)

    Michael, G.E.; Anders, D.E.; Law, B.E.


    Geochemical analyses of coal samples from the Upper Cretaceous Fruitland Formation in the San Juan Basin of New Mexico and Colorado were used to determine thermal maturity, type of kerogen, and hydrocarbon generation potential. Mean random vitrinite reflectance (%Rm) of the Fruitland coal ranges from 0.42 to 1.54%. Rock-Eval pyrolysis data and saturated to aromatic hydrocarbon ratio indicate that the onset of thermal hydrocarbon generation begins at about 0.60% Rm and peak generation occurs at about 0.85% Rm. Several samples have hydrogen index values between 200 and 400, indicating some potential for liquid hydrocarbon generation and a mixed Type III and II kerogen. Pentacyclic and tricyclic terpanes, steranes, aromatic steroids and methylphenanthrene maturity parameters were observed through the complete range of thermal maturity in the Fruitland coals. Aromatic pentacyclic terpanes, similar to those found in brown coals of Australia, were observed in low maturity samples, but not found above 0.80% Rm. N-alkane depleted coal samples, which occur at a thermal maturity of approx. 0.90% Rm, paralleling peak hydrocarbon generation, are fairly widespread throughout the basin. Depletion of n-alkanes in these samples may be due to gas solution stripping and migration fromthe coal seams coincident with the development of pressure induced fracturing due to hydrocarbon generation; however, biodegradation may also effect these samples. ?? 1993.

  15. Effect of temperature on sandstone permeability

    DEFF Research Database (Denmark)

    Rosenbrand, Esther; Kjøller, Claus

    assumptions would be required in order to estimate sandstone permeability based on the Kozeny equation. An effective specific surface area per pore volume for permeability was estimated by using image analysis and pore size distributions as from nuclear magnetic resonance (NMR) transverse relaxation data...... be determined based on the Klinkenberg (1941) procedure, which accounts for effects on permeability of gas slip on the fluid-solid interface by means of several permeability measurements with different pore pressures. A comparison between the equivalent pore sizes as estimated using the Kozeny equation...... at 80°C than at 20°C; at 80°C the main effect might be due to an alteration of pore fluid rheology, whereas at 20°C particles might be filtered in pore constrictions. DLVO theory (Derjaguin and Landau (1941); Verwey and Overbeek (1948)) was used to compare effects of temperature and salinity on surface...

  16. Dilatant hardening of fluid-saturated sandstone (United States)

    Makhnenko, Roman Y.; Labuz, Joseph F.


    The presence of pore fluid in rock affects both the elastic and inelastic deformation processes, yet laboratory testing is typically performed on dry material even though in situ the rock is often saturated. Techniques were developed for testing fluid-saturated porous rock under the limiting conditions of drained, undrained, and unjacketed response. Confined compression experiments, both conventional triaxial and plane strain, were performed on water-saturated Berea sandstone to investigate poroelastic and inelastic behavior. Measured drained response was used to calibrate an elasto-plastic constitutive model that predicts undrained inelastic deformation. The experimental data show good agreement with the model: dilatant hardening in undrained triaxial and plane strain compression tests under constant mean stress was predicted and observed.

  17. The experimental modeling of gas percolation mechanisms in a coal-measure tight sandstone reservoir: A case study on the coal-measure tight sandstone gas in the Upper Triassic Xujiahe Formation, Sichuan Basin, China

    Directory of Open Access Journals (Sweden)

    Shizhen Tao


    Full Text Available Tight sandstone gas from coal-measure source rock is widespread in China, and it is represented by the Xujiahe Formation of the Sichuan Basin and the Upper Paleozoic of the Ordos Basin. It is affected by planar evaporative hydrocarbon expulsion of coal-measure source rock and the gentle structural background; hydrodynamics and buoyancy play a limited role in the gas migration-accumulation in tight sandstone. Under the conditions of low permeability and speed, non-Darcy flow is quite apparent, it gives rise to gas-water mixed gas zone. In the gas displacing water experiment, the shape of percolation flow curve is mainly influenced by core permeability. The lower the permeability, the higher the starting pressure gradient as well as the more evident the non-Darcy phenomenon will be. In the gas displacing water experiment of tight sandstone, the maximum gas saturation of the core is generally less than 50% (ranging from 30% to 40% and averaging at 38%; it is similar to the actual gas saturation of the gas zone in the subsurface core. The gas saturation and permeability of the core have a logarithm correlation with a correlation coefficient of 0.8915. In the single-phase flow of tight sandstone gas, low-velocity non-Darcy percolation is apparent; the initial flow velocity (Vd exists due to the slippage effect of gas flow. The shape of percolation flow curve of a single-phase gas is primarily controlled by core permeability and confining pressure; the lower the permeability or the higher the confining pressure, the higher the starting pressure (0.02–0.08 MPa/cm, whereas, the higher the quasi-initial flow speed, the longer the nonlinear section and the more obvious the non-Darcy flow will be. The tight sandstone gas seepage mechanism study shows that the lower the reservoir permeability, the higher the starting pressure and the slower the flow velocity will be, this results in the low efficiency of natural gas migration and accumulation as well as

  18. Analysis of single oil-bearing fluid inclusions in mid-Proterozoic sandstones (Roper Group, Australia) (United States)

    Siljeström, Sandra; Volk, Herbert; George, Simon C.; Lausmaa, Jukka; Sjövall, Peter; Dutkiewicz, Adriana; Hode, Tomas


    Hydrocarbons and organic biomarkers extracted from black shales and other carbonaceous sedimentary rocks are valuable sources of information on the biodiversity and environment of early Earth. However, many Precambrian hydrocarbons including biomarkers are suspected of being younger contamination. An alternative approach is to study biomarkers trapped in oil-bearing fluid inclusions by bulk crushing samples and subsequently analysing the extracted hydrocarbons with gas chromatography-mass spectrometry. However, this method does not constrain the hydrocarbons to one particular oil inclusion, which means that if several different generations of oil inclusions are present in the sample, a mix of the content from these oil inclusions will be analysed. In addition, samples with few and/or small inclusions are often below the detection limit. Recently, we showed that it is possible to detect organic biomarkers in single oil-bearing fluid inclusions using time-of-flight secondary ion mass spectrometry (ToF-SIMS). In the present study, single fluid inclusion analysis has been performed on Proterozoic samples for the first time. Four individual oil-bearing fluid inclusions, found in 1430 Ma sandstone from the Roper Superbasin in Northern Australia, were analysed with ToF-SIMS. The ToF-SIMS spectra of the oil in the different inclusions are very similar to each other and are consistent with the presence of n-alkanes/branched alkanes, monocyclic alkanes, bicyclic alkanes, aromatic hydrocarbons, and tetracyclic and pentacyclic hydrocarbons. These results are in agreement with those obtained from bulk crushing of inclusions trapped in the same samples. The capability to analyse the hydrocarbon and biomarker composition of single oil-bearing fluid inclusions is a major breakthrough, as it opens up a way of obtaining molecular compositional data on ancient oils without the ambiguity of the origin of these hydrocarbons. Additionally, this finding suggests that it will be possible

  19. Basical characteristics of fluid geologic process of interlayer oxidation zone sandstone-typeuranium deposit

    Institute of Scientific and Technical Information of China (English)

    WU; BoLin; LIU; ChiYang; WANG; JianQiang


    This paper reveals the physicochemical properties such as component, formulation, genesis, tem- perature, pH, Eh, salinity and pressure of all main alteration fluid of interlayer oxidation zone sand- stone-type uranium deposits after studying the geologic process and geochemistry of internal typical sandstone-type uranium deposits such as Shihongtan deposit in the Turpan-Hami basin, 512 deposit in the Yili basin, Dongsheng deposit in the Ordos basin. The composition of fluid can be divided into two parts based on the analysis of inclusion: one can be affirmed as atmospheric water with ordinary temperature epigenesist according to the character of hydrogen and oxygen isotope of inclusion, the other is natural gas containing gaseous hydrocarbon like CH4, and CO2 as well as a little H2S, CO, H2, N2 and so on, it always contains a small quantity of hydrocarbon liquid in petroliferous basins. The fluid property of oxidation alteration zone is always oxidation alkaline, and neutrality or weak acid-weak alkaline and reducibility during the metallizing process, but at secondary reduction or deoxidization zone it becomes strong reduction alkaline. Oxygenic groundwater in the fluid is the activate and mig- ratory medium of uranium element, but the gaseous hydrocarbon like CH4 as well as H2, H2S, CO from natural gas is the important sedimentary reducer of uranium mineral; the transformation of pH,Eh in fluid environment is the main reason for the formation of uranium metallization.

  20. Attenuation of Landfill Leachate In Unsaturated Sandstone (United States)

    Butler, A. P.; Brook, C.; Godley, A.; Lewin, K.; Young, C. P.

    Landfill leachate emanating from old "dilute and disperse" sites represents a potential (and in many cases actual) threat to the integrity of groundwater. Indeed, this concern has been included in EU legislation (80/86/EEC), where key contaminants (e.g. ammonia, various toxic organic compounds and heavy metals) are explicitly highlighted in terms of their impact on groundwater. In the UK, whilst there are a substantial number of unlined landfills sited on major aquifers, many of these are in locations where there is a substantial unsaturated zone. Thus, there exists the opportunity for the modification and attenuation of contaminants prior to it encountering the water table. An understanding of likely changes in leachate content and concentrations at such sites will enable a more comprehensive assessment of the potential risks and liabilities posed by such sites to be evaluated. The Burntstump landfill, situated 8 km north of Nottingham (UK), is sited on an outcrop of Sherwood sandstone. The fine friable sand has been quarried since the 1960s and the excavated volume used to store municipal waste. Filling at the site commenced in the mid 1970s and originally was unlined. In 1978 the first of what was to become a series of boreholes was installed within an area of roughly 5 m radius over one of the original waste cells. Cores of the waste and underlying sandstone were extracted and analysed for a range of physical and chemical parameters. The most recent set of analyses were obtained in 2000. The series of investigations therefore provide an important record of leachate migration and modification through the unsaturated zone for over twenty years. The progression of the leachate front is clearly delineated by the chloride concentration profile with an average velocity of around 1.6 m.yr-1. Combining this value with an average (and reasonably uniform) measured moisture content of about 7% gives a mean inter-granular specific discharge of 110 mm.yr-1. An interesting

  1. Sedimentary response to tectonism in the extensional Chihuahua trough, Cretaceous of Southern North America (United States)

    Budhathoki, P.; Langford, R. P.; Pavlis, T. L.


    During the Jurassic and Cretaceous, the Chihuahua Trough formed an extensional basin, extending from the Gulf of Mexico to Southern Arizona, along the Present Border of the United States and Mexico. West of the Big Bend of Texas, Jurassic and Cretaceous sediments are less than 150 m thick, and in many areas are absent. The sedimentary package thickens to over 3km within the trough. The Albian Cox Sandstone is one of the most areally extensive formations and consists of interbedded fluvial coastal and shallow marine sandstones and shales. In this study area, shales (10-70 m) are thicker more than sandstone beds (2-10 m). This unit is overlain by Finlay formation, a fine crystalline gray limestone and underlain by Bluff Mesa formation, a fossiliferous shallow marine limestone. Cross-bedded, brown, fine to medium grained sandstone, interbedded with siltstone, shale and limestone are characteristic lithology of the Cox. The Indio Mountains of Trans-Pecos Texas offer an ideal location to study how this package accommodates the deformation associated with the subsiding Chihuahua trough. A continuous outcrop extends over 30 km oblique to the basin margin and thickens from approximately 375 m on the northern side to 437 m on the southern side of the 10 km section studied so far. One important mechanism is rotation of the strata into the basin, followed by truncation along sequence boundaries. The lower two sequence in the southern Indio mountains are rotated down to the basin relative to Finlay. The lowest sequences thicken from an erosional pinch out towards the South. Shale beds thicken within the rotated strata and accommodate some of the tilting. For example, Thickness of the shale bed varies from 18 m to 70 m within a 2 km distance. However, erosional truncation of the tilted strata accounts for most of the increases in thickness within sequences. The base of the formation has been rotated about 6 degrees south relative to the top of the formation. Another observed

  2. Cretaceous Onlap, Gulf of Mexico Basin [cretonlapg (United States)

    U.S. Geological Survey, Department of the Interior — The maximum extent of Cretaceous onlap is generalized from Plate 3, Structure at the base and subcrop below Mesozoic marine section, Gulf of Mexico Basin (compiled...

  3. Evolution of pore space in sandstones in relation to diagenesis

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, G.


    Results are described from studying the collector properties of a bed of sandstones of Yan-10 at the oil field Malin of the Ordosskiy oil and gas basin. The bed is represented by ancient river sandstones of the Jurassic age occurring on eroded surface of the Triassic deposits (Yangan series) and covered with bed of coal deposits Yan-9. The following conclusions were drawn from the results of the studies. Evolution of the pore space actually is the process of gradual substitution of the primary pores by secondary; in this case decrease in porosity in the quartz sandstones occurs mainly because of depositing in the pores of authigenic minerals, and in the sandstones whose grains consist of minerals with lower mechanical strength, because of packing. Secondary porosity develops because of dissolving and kaolinization in the sandstones with high content of feldspars. This process is possibly associated with decarboxilation of organic matter of interlayers of coal and calcareous shales under the influence of increased temperature in the submersion process. Since it has been established that considerable influence on porosity comes from the mineralogical position of the sandstones controlled by the sources of formation, in order to reveal the zones for development of primary and secondary porosity, it is very important to reveal the sources of removal of detrital rocks. A study was also made of the influence of diagenesis on uniformity and texture of the sandstones (by the methods of curves of capillary pressure).

  4. The hydrocarbon sphere

    Energy Technology Data Exchange (ETDEWEB)

    Mandev, P.


    The hydrocarbon sphere is understood to be the area in which hydrocarbon compounds are available. It is believed that the lower boundary on the hydrocarbon sphere is most probably located at a depth where the predominant temperatures aid in the destruction of hydrocarbons (300 to 400 degrees centigrade). The upper limit on the hydrocarbon sphere obviously occurs at the earth's surface, where hydrocarbons oxidize to H20 and CO2. Within these ranges, the occurrence of the hydrocarbon sphere may vary from the first few hundred meters to 15 kilometers or more. The hydrocarbon sphere is divided into the external (mantle) sphere in which the primary gas, oil and solid hydrocarbon fields are located, and the internal (metamorphic) sphere containing primarily noncommercial accumulations of hydrocarbon gases and solid carbon containing compounds (anthraxilite, shungite, graphite, etc.) based on the nature and scale of hydrocarbon compound concentrations (natural gas, oil, maltha, asphalt, asphaltite, etc.).

  5. Early Cretaceous angiosperms and beetle evolution


    Bo eWang; Haichun eZhang; Edmund eJarzembowski


    The Coleoptera (beetles) constitute almost one–fourth of all known life-forms on earth. They are also among the most important pollinators of flowering plants, especially basal angiosperms. Beetle fossils are abundant, almost spanning the entire Early Cretaceous, and thus provide important clues to explore the co-evolutionary processes between beetles and angiosperms. We review the fossil record of some Early Cretaceous polyphagan beetles including Tenebrionoidea, Scarabaeoidea, Curculionoide...

  6. Reservoir heterogeneity in carboniferous sandstone of the Black Warrior basin. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Kugler, R.L.; Pashin, J.C.; Carroll, R.E.; Irvin, G.D.; Moore, H.E.


    Although oil production in the Black Warrior basin of Alabama is declining, additional oil may be produced through improved recovery strategies, such as waterflooding, chemical injection, strategic well placement, and infill drilling. High-quality characterization of reservoirs in the Black Warrior basin is necessary to utilize advanced technology to recover additional oil and to avoid premature abandonment of fields. This report documents controls on the distribution and producibility of oil from heterogeneous Carboniferous reservoirs in the Black Warrior basin of Alabama. The first part of the report summarizes the structural and depositional evolution of the Black Warrior basin and establishes the geochemical characteristics of hydrocarbon source rocks and oil in the basin. This second part characterizes facies heterogeneity and petrologic and petrophysical properties of Carter and Millerella sandstone reservoirs. This is followed by a summary of oil production in the Black Warrior basin and an evaluation of seven improved-recovery projects in Alabama. In the final part, controls on the producibility of oil from sandstone reservoirs are discussed in terms of a scale-dependent heterogeneity classification.

  7. Reservoir heterogeneity in Carboniferous sandstone of the Black Warrior basin. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Kugler, R.L.; Pashin, J.C.; Carroll, R.E.; Irvin, G.D.; Moore, H.E.


    Although oil production in the Black Warrior basin of Alabama is declining, additional oil may be produced through improved recovery strategies, such as waterflooding, chemical injection, strategic well placement, and infill drilling. High-quality characterization of reservoirs in the Black Warrior basin is necessary to utilize advanced technology to recover additional oil and to avoid premature abandonment of fields. This report documents controls on the distribution and producibility of oil from heterogeneous Carboniferous reservoirs in the Black Warrior basin of Alabama. The first part of the report summarizes the structural and depositional evolution of the Black Warrior basin and establishes the geochemical characteristics of hydrocarbon source rocks and oil in the basin. This second part characterizes facies heterogeneity and petrologic and petrophysical properties of Carter and Millerella sandstone reservoirs. This is followed by a summary of oil production in the Black Warrior basin and an evaluation of seven improved-recovery projects in Alabama. In the final part, controls on the producibility of oil from sandstone reservoirs are discussed in terms of a scale-dependent heterogeneity classification.

  8. Lamniform shark teeth from the late cretaceous of southernmost South America (Santa Cruz province, Argentina). (United States)

    Schroeter, Elena R; Egerton, Victoria M; Ibiricu, Lucio M; Lacovara, Kenneth J


    Here we report multiple lamniform shark teeth recovered from fluvial sediments in the (Campanian-Maastrichtian) Cerro Fortaleza Formation, Santa Cruz Province, Argentina. This small tooth assemblage is compared to various lamniform sharks possessing similar dental morphologies, including Archaeolamna, Cretalamna, Dwardius, Dallasiella, and Cretodus. Although the teeth share numerous morphological features with the genus Archaeolamna, including a developed neck that maintains a relatively consistent width along the base of the crown, the small sample size and incomplete nature of these specimens precludes definitive taxonomic assignment. Regardless, the discovery of selachian teeth unique from those previously described for the region broadens the known diversity of Late Cretaceous South American sharks. Additionally, the discovery of the teeth in fluvial sandstone may indicate a euryhaline paleobiology in the lamniform taxon or taxa represented by this tooth assemblage.

  9. Lamniform shark teeth from the late cretaceous of southernmost South America (Santa Cruz province, Argentina.

    Directory of Open Access Journals (Sweden)

    Elena R Schroeter

    Full Text Available Here we report multiple lamniform shark teeth recovered from fluvial sediments in the (Campanian-Maastrichtian Cerro Fortaleza Formation, Santa Cruz Province, Argentina. This small tooth assemblage is compared to various lamniform sharks possessing similar dental morphologies, including Archaeolamna, Cretalamna, Dwardius, Dallasiella, and Cretodus. Although the teeth share numerous morphological features with the genus Archaeolamna, including a developed neck that maintains a relatively consistent width along the base of the crown, the small sample size and incomplete nature of these specimens precludes definitive taxonomic assignment. Regardless, the discovery of selachian teeth unique from those previously described for the region broadens the known diversity of Late Cretaceous South American sharks. Additionally, the discovery of the teeth in fluvial sandstone may indicate a euryhaline paleobiology in the lamniform taxon or taxa represented by this tooth assemblage.

  10. A two scale analysis of tight sandstones (United States)

    Adler, P. M.; Davy, C. A.; Song, Y.; Troadec, D.; Hauss, G.; Skoczylas, F.


    Tight sandstones have a low porosity and a very small permeability K. Available models for K do not compare well with measurements. These sandstones are made of SiO_2 grains, with a typical size of several hundreds of micron. These grains are separated by a network of micro-cracks, with sizes ranging between microns down to tens of nm. Therefore, the structure can be schematized by Voronoi polyhedra separated by plane and permeable polygonal micro-cracks. Our goal is to estimate K based on a two scale analysis and to compare the results to measurements. For a particular sample [2], local measurements on several scales include FIB/SEM [3], CMT and 2D SEM. FIB/SEM is selected because the peak pore size given by Mercury Intrusion Porosimetry is of 350nm. FIB/SEM imaging (with 50 nm voxel size) identifies an individual crack of 180nm average opening, whereas CMT provides a connected porosity (individual crack) for 60 nm voxel size, of 4 micron average opening. Numerical modelling is performed by combining the micro-crack network scale (given by 2D SEM) and the 3D micro-crack scale (given by either FIB/SEM or CMT). Estimates of the micro-crack density are derived from 2D SEM trace maps by counting the intersections with scanlines, the surface density of traces, and the number of fracture intersections. K is deduced by using a semi empirical formula valid for identical, isotropic and uniformly distributed fractures [1]. This value is proportional to the micro-crack transmissivity sigma. Sigma is determined by solving the Stokes equation in the micro-cracks measured by FIB/SEM or CMT. K is obtained by combining the two previous results. Good correlation with measured values on centimetric plugs is found when using sigma from CMT data. The results are discussed and further research is proposed. [1] Adler et al, Fractured porous media, Oxford Univ. Press, 2012. [2] Duan et al, Int. J. Rock Mech. Mining Sci., 65, p75, 2014. [3] Song et al, Marine and Petroleum Eng., 65, p63

  11. Factors controlling localization of uranium deposits in the Dakota Sandstone, Gallup and Ambrosia Lake mining districts, McKinley County, New Mexico (United States)

    Pierson, Charles Thomas; Green, Morris W.


    Geologic studies were made at all of the uranium mines and prospects in the Dakota Sandstone of Early(?) and Late Cretaceous age in the Gallup mining district, McKinley County, New Mexico. Dakota mines in the adjacent Ambrosia Lake mining district were visited briefly for comparative purposes. Mines in the eastern part of the Gallup district, and in the Ambrosia Lake district, are on the Chaco slope of the southern San Juan Basin in strata which dip gently northward toward the central part of the basin. Mines in the western part of the Gallup district are along the Gallup hogback (Nutria monocline) in strata which dip steeply westward into the Gallup sag. Geologic factors which controlled formation of the uranium deposits in the Dakota Sandstone are: (1) a source of uranium, believed to be uranium deposits of the underlying Morrison Formation of Late Jurassic age; (2) the accessibility to the Dakota of uranium-bearing solutions from the Morrison; (3) the presence in the Dakota of permeable sandstone beds overlain by impermeable carbonaceous shale beds; and (4) the occurrence within the permeable Dakota sandstone beds of carbonaceous reducing material as bedding-plane laminae, or as pockets of carbonaceous trash. Most of the Dakota uranium deposits are found in the lower part of the formation in marginal-marine distributary-channel sandstones which were deposited in the backshore environment. However, the Hogback no. 4 (Hyde) Mine (Gallup district) occurs in sandy paludal shale of the backshore environment, and another deposit, the Silver Spur (Ambrosia Lake district), is found in what is interpreted to be a massive beach or barrier-bar sandstone of the foreshore environment in the upper part of the Dakota. The sedimentary depositional environment most favorable for the accumulation of uranium is that of backshore areas lateral to main distributary channels, where levee, splay, and some distributary-channel sandstones intertongue with gray carbonaceous shales and

  12. Depositional sequence architecture and filling response model of the Cretaceous in the Kuqa depression, the Tarim basin

    Institute of Scientific and Technical Information of China (English)

    LIN; Changsong; WANG; Qinghua; XIAO; Jianxin; WANG; Guoli


    The Cretaceous system of the Kuqa depression is a regional scale (second order) depositional sequence defined by parallel unconformities or minor angular unconformities. It can be divided into four third-order sequence sets, eleven third-order sequences and tens of fourth- and fifth-order sequences. It consists generally of a regional depositional cycle from transgression to regression and is composed of three sets of facies associations: alluvial-fluvial, braided river-deltaic and lacustrine-deltaic facies associations. They represent the lowstand, transgressive and highstand facies tracts within the second-order sequence. The tectonic subsidence curve reconstructed by backstripping technique revealed that the Cretaceous Kuqa depression underwent a subsidence history from early accelerated subsidence, middle rapid subsidence and final slower subsidence phases during the Cretaceous time, with the correspondent tectonic subsidence rates being 30-35 m/Ma, 40-45 m/Ma and 5-10 m/Ma obtained from northern foredeep. This is likely attributed to the foreland dynamic process from early thrust flexural subsidence to late stress relaxation and erosion rebound uplift. The entire sedimentary history and the development of the three facies tracts are a response to the basin subsidence process. The slower subsidence foreland gentle slope was a favorable setting for the formation of braided fluvial deltaic systems during the late period of the Cretaceous, which comprise the important sandstone reservoirs in the depression. Sediment records of impermanent marine transgression were discovered in the Cretaceous and the major marine horizons are correctable to the highstands of the global sea level during the period.

  13. The paleohydrology of Lower Cretaceous seasonal wetlands, Isle of Wight, southern England

    Energy Technology Data Exchange (ETDEWEB)

    Wright, V.P.; Taylor, K.G.; Beck, V.H.


    The floodplain deposits of the Wealden Group (Lower Cretaceous) of the Isle of Wight, southern England, were formed in a seasonal wetland setting, a type of environment widespread today along higher-order tropical and subtropical river systems but rarely identified in the geological record. The unit consists of four main lithofacies: sheet sandstones with dinosaur footprint casts; green-gray mudstones with vertebrate remains, abundant lignite, pyrite, and siderite; spectacularly color-mottled mudstones with goethite and locally pseudo-anticlines; and red mudstones with pseudo-anticlines, hematite, and carbonate nodules. The sheet sandstones are interpreted as crevasse deposits; the green-gray mudstones were deposited in shallow ponds on the floodplain, which acted as sinks for debris released by local floods following wildfires; the mottled mudstones represent surface-water gley soils formed in seasonally waterlogged areas; and the red mudstones resemble present-day Vertisols that formed on topographically elevated areas only intermittently flooded. These mudstones show vertical transitions from one to another, and although they could be interpreted as components of simple catenas, the absence of associated facies changes implies that topographic differences were not the only control. It is proposed that these three mudstone types formed as seasonal wetland catenas, in which differences in soil drainage conditions resulted from variations in the flooding hydroperiod affecting areas with minor relief differences, rather than drainage variability simply reflecting static topographic differences. Such seasonal wetland systems are rarely documented in the stratigraphic record despite being a widespread environment in present-day tropical regions, and the Wealden deposits are used to identify criteria for the recognition of this important environment in the rock record. These southern English wetlands are compared with other Lower Cretaceous wetlands from northern Spain

  14. Refuge Management Plan: Sandstone Unit Rice Lake National Wildlife Refuge (United States)

    US Fish and Wildlife Service, Department of the Interior — Part I of this management plan for the Sandstone Unit of Rice Lake NWR summarizes background information on the location, history, environment, resources,...

  15. Size effect of sandstone after high temperature under uniaxial compression

    Institute of Scientific and Technical Information of China (English)

    SU Hai-jian; JING Hong-wen; MAO Xian-biao; ZHAO Hong-hui; YIN Qian; WANG Chen


    Uniaxial compression tests on sandstone samples with five different sizes after high temperature processes were performed in order to investigate the size effect and its evolution. The test results show that the density, longitudinal wave velocity, peak strength, average modulus and secant modulus of sandstone decrease with the increase of temperature, however, peak strain increases gradually. With the increase of ratio of height to diameter, peak strength of sandstone decreases, which has an obvious size effect. A new theoretical model of size effect of sandstone material considering the influence of temperature is put forward, and with the increase of temperature, the size effect is more apparent. The threshold decreases gradually with the increase of temperature, and the deviations of the experimental values and the theoretical values are between 0.44% and 6.06%, which shows quite a credibility of the theoretical model.

  16. Study on the cutting plane friction law of sandstone

    Institute of Scientific and Technical Information of China (English)

    ZHAI Ying-da (翟英达); KANG Li-xun(康立勋)


    The friction characteristics of rock damage plane have important impact on the stability of block structure formed after the stratum is broken. The mechanics properties of rock damage plane are described by parameters such as roughness coefficient, wall compress strength and basic friction angle. These three coefficients for fine grain sandstone and medium-granular sandstone and grit sandstone are test. The friction stress is researched at the condition of different normal compressive stress acting on the tension damage plane. The friction law of tension damage plane of sandstone abided by is summed up. This law will provide scientific basis for block structure stability judging in basic roof stratum and roof pressure intensity calculating.

  17. Reservoir zonation based on statistical analyses: A case study of the Nubian sandstone, Gulf of Suez, Egypt (United States)

    El Sharawy, Mohamed S.; Gaafar, Gamal R.


    Both reservoir engineers and petrophysicists have been concerned about dividing a reservoir into zones for engineering and petrophysics purposes. Through decades, several techniques and approaches were introduced. Out of them, statistical reservoir zonation, stratigraphic modified Lorenz (SML) plot and the principal component and clustering analyses techniques were chosen to apply on the Nubian sandstone reservoir of Palaeozoic - Lower Cretaceous age, Gulf of Suez, Egypt, by using five adjacent wells. The studied reservoir consists mainly of sandstone with some intercalation of shale layers with varying thickness from one well to another. The permeability ranged from less than 1 md to more than 1000 md. The statistical reservoir zonation technique, depending on core permeability, indicated that the cored interval of the studied reservoir can be divided into two zones. Using reservoir properties such as porosity, bulk density, acoustic impedance and interval transit time indicated also two zones with an obvious variation in separation depth and zones continuity. The stratigraphic modified Lorenz (SML) plot indicated the presence of more than 9 flow units in the cored interval as well as a high degree of microscopic heterogeneity. On the other hand, principal component and cluster analyses, depending on well logging data (gamma ray, sonic, density and neutron), indicated that the whole reservoir can be divided at least into four electrofacies having a noticeable variation in reservoir quality, as correlated with the measured permeability. Furthermore, continuity or discontinuity of the reservoir zones can be determined using this analysis.

  18. Quantifying Porosity through Automated Image Collection and Batch Image Processing: Case Study of Three Carbonates and an Aragonite Cemented Sandstone

    Directory of Open Access Journals (Sweden)

    Jim Buckman


    Full Text Available Modern scanning electron microscopes often include software that allows for the possibility of obtaining large format high-resolution image montages over areas of several square centimeters. Such montages are typically automatically acquired and stitched, comprising many thousand individual tiled images. Images, collected over a regular grid pattern, are a rich source of information on factors such as variability in porosity and distribution of mineral phases, but can be hard to visually interpret. Additional quantitative data can be accessed through the application of image analysis. We use backscattered electron (BSE images, collected from polished thin sections of two limestone samples from the Cretaceous of Brazil, a Carboniferous limestone from Scotland, and a carbonate cemented sandstone from Northern Ireland, with up to 25,000 tiles per image, collecting numerical quantitative data on the distribution of porosity. Images were automatically collected using the FEI software Maps, batch processed by image analysis (through ImageJ, with results plotted on 2D contour plots with MATLAB. These plots numerically and visually clearly express the collected porosity data in an easily accessible form, and have application for the display of other data such as pore size, shape, grain size/shape, orientation and mineral distribution, as well as being of relevance to sandstone, mudrock and other porous media.

  19. Late Cretaceous- Cenozoic history of deciduousness and the terminal Cretaceous event. (United States)

    Wolfe, J.A.


    Deciduousness in mesic, broad-leaved plants occurred in disturbed, middle-latitude environments during the Late Cretaceous. Only in polar environments in the Late Cretaceous was the deciduous element dominant, although of low diversity. The terminal Cretaceous event resulted in wide-spread selection for plants of deciduous habit and diversification of deciduous taxa, thus leaving a lasting imprint on Northern Hemisphere vegetation. Various environmental factors have played important roles in subsequent diversification of mesic, broad-leaved deciduous taxa and in origination and decline of broad-leaved deciduous forests. Low diversity and rarity of mesic deciduous plants in the post-Cretaceous of the Southern Hemisphere indicate that the inferred 'impact winter' of the terminal Cretaceous event had little effect on Southern Hemisphere vegetation and climate. -Author

  20. Main controlling factors and exploration potential of hydrocarbon reservoirs in North Gabon sub-Basin%北加蓬次盆油气成藏主控因素分析及勘探潜力评价

    Institute of Scientific and Technical Information of China (English)



    北加蓬次盆是一个裂谷盆地与被动大陆边缘盆地叠加形成的中、新生代复合盆地,油气成藏明显受构造运动、沉积环境、盐岩变形等地质因素的控制。盆地东部因抬升剥蚀而遭受不同程度的破坏,烃源岩及油气藏没有很好地保存,导致了东部构造带和西部构造带油气资源贫富差异较大。沉积环境影响储层发育,上白垩统浊积扇砂体和三角洲砂体是盐上层系最重要的储层,油气圈闭的形成与盐岩构造活动密切相关,圈闭类型丰富多彩。根据盐上层系烃源岩和浊积砂体储层分布等地质规律研究,北加蓬次盆大西洋深水斜坡带的中南部处于Azile组主力烃源岩分布区,油气源供给条件优越,储层发育,油气成藏条件得天独厚,是盆地油气勘探最有利的地区。%The North Gabon sub⁃Basin is a Mesozoic-Cenozoic rift and divergent margin basin. The oil and gas reservoirs in the basin were controlled by tectonic movements, sedimentary environments and salt structures. The east of the basin was eroded due to regional uplift, and source rocks and hydrocarbon reservoirs were destroyed, leading to a significant difference of hydrocarbon potential between the east and the west tectonic belts. Sedimen⁃tary environments impacted reservoirs. The Upper Cretaceous turbidity sandstones and offshore sandstones were important reservoirs for the post salt layers. Various traps developed, which were related to salt structure activi⁃ties. Based on research of the turbidity sandstones and offshore sandstones of the post⁃salt layers, the main hydro⁃carbon reservoirs of the North Gabon sub⁃Basin mainly lie on the middle⁃south, deep ocean slope belt, which is the center of the major source rocks of the Azile Formation. Thanks to favorable sourcing and reserving condi⁃tions, the middle⁃south, deep ocean slope belthas considerable hydrocarbon prospects.

  1. Micropore Structure Representation of Sandstone in Petroleum Reservoirs Using an Atomic Force Microscope

    Institute of Scientific and Technical Information of China (English)

    BAI Yong-Qiang; ZHU Xing; WU Jun-Zheng; BAI Wen-Guang


    @@ The pore structure of sandstone in an oil reservoir is investigated using atomic force microscopy(AFM).At nanoscale resolution,AFM images of sandstone show us the fine structure.The real height data of images display the three-dimensional space structure of sandstone effectively.The three-dimensional analysis results show that the AFM images of sandstone have unique characteristics that,like fingerprints,can identify different structural properties of sandstones.The results demonstrate that AFM is an effective method used to represent original sandstone in petroleum reservoirs,and may help geologists to appreciate the sandstone in oil reservoirs fully.

  2. Understanding creep in sandstone reservoirs - theoretical deformation mechanism maps for pressure solution in granular materials (United States)

    Hangx, Suzanne; Spiers, Christopher


    Subsurface exploitation of the Earth's natural resources removes the natural system from its chemical and physical equilibrium. As such, groundwater extraction and hydrocarbon production from subsurface reservoirs frequently causes surface subsidence and induces (micro)seismicity. These effects are not only a problem in onshore (e.g. Groningen, the Netherlands) and offshore hydrocarbon fields (e.g. Ekofisk, Norway), but also in urban areas with extensive groundwater pumping (e.g. Venice, Italy). It is known that fluid extraction inevitably leads to (poro)elastic compaction of reservoirs, hence subsidence and occasional fault reactivation, and causes significant technical, economic and ecological impact. However, such effects often exceed what is expected from purely elastic reservoir behaviour and may continue long after exploitation has ceased. This is most likely due to time-dependent compaction, or 'creep deformation', of such reservoirs, driven by the reduction in pore fluid pressure compared with the rock overburden. Given the societal and ecological impact of surface subsidence, as well as the current interest in developing geothermal energy and unconventional gas resources in densely populated areas, there is much need for obtaining better quantitative understanding of creep in sediments to improve the predictability of the impact of geo-energy and groundwater production. The key problem in developing a reliable, quantitative description of the creep behaviour of sediments, such as sands and sandstones, is that the operative deformation mechanisms are poorly known and poorly quantified. While grain-scale brittle fracturing plus intergranular sliding play an important role in the early stages of compaction, these time-independent, brittle-frictional processes give way to compaction creep on longer time-scales. Thermally-activated mass transfer processes, like pressure solution, can cause creep via dissolution of material at stressed grain contacts, grain

  3. Geochemistry of hydrocarbons of the Terek-Caspian trough

    Directory of Open Access Journals (Sweden)

    N.Sh. Yandarbiev


    Full Text Available Within the Terek-Caspian oil and gas bearing basin of the Eastern Ciscaucasia, oil deposits occur in a wide stratigraphic range of rocks of the Mesozoic-Cenozoic section, from the Jurassic, at depths from 5800 to 200 m. In the sedimentary section, carbonate and terrigenous Middle Jurassic, Lower Cretaceous, Oligocene-Lower Miocene and Miocene oil-mother rocks are distinguished. Organic matter from them have different geochemical characteristics and different maturity to realize the generation potential. The article presents the results of a comprehensive study of potential petroleum-bearing rocks and hydrocarbon fluids from the Terek-Sunzha folded zone of the Terek-Caspian Trough, including lithological, chemical-bituminological, pyrolytic, chromatographic and chromatographic-mass spectrometry investigations. A detailed description of hydrocarbon fluids at the molecular level and genetic correlations of oil-oil and oil-organic matter are given. Specific features of the oil deposits of the Mesozoic-Cenozoic section are noted. Among the studied bitumens, the chromatographic characteristics of the extractable organic matter from the Khadum carbonate-clayey deposits and oils from the Cretaceous and Neogene reservoirs are most similar. The composition of a complex natural mixture of hydrocarbons from various sources, with different maturation during the geological history of the region, does not allow making unambiguous conclusions about the source or sources of hydrocarbons for the deposits of the Terek-Caspian Trough.

  4. Raman characteristics of hydrocarbon and hydrocarbon inclusions

    Institute of Scientific and Technical Information of China (English)

    ZHANG Nai; TIAN ZuoJi; LENG YingYing; WANG HuiTong; SONG FuQing; MENG JianHua


    The Raman spectrograms of hydrocarbon standard samples show that: (1) the Raman spectrogram of normal paraffin has very strong peaks of methyl and methylene (from 2700 cm-1 to 2970 cm-1); (2)branch methyl has the particular peak of 748 cm-1±; (3) six cyclic has the particular peak of 804 cm-1±; (4)phenyl has two particular peaks of 988 cm-1± and 3058 cm-1± and the 988 cm-1± peak is stronger than the 3058 cm-1± peak; and (5) hexene has three alkenyl spectrum peaks of 1294 cm-1±, 1635 cm-1± and 2996 cm-1±, with the 1635 cm-1± peak being the strongest, showing that the number of carbon in hydrocarbon does not affect its Raman spectrogram, and the hydrocarbon molecular structure and base groups affect its Raman spectrogram, the same hydrocarbons (such as normal paraffin) have the same Raman spectrogram; the types (such as CH4, C2H6, C3H8) and the content of hydrocarbon in oil inclusions are not estimated by their characteristic Raman peaks. According to the Raman spectrograms of hydrocarbon compositions, the Raman spectrogram of hydrocarbon inclusion can be divided into five types: saturated hydrocarbon Raman spectrogram, fluoresce Raman spectrogram, saturated hydrocarbon bitumen Raman spectrogram, bitumen Raman spectrogram, and ethane Raman spectrogram.And according to the characteristics of Raman spectrogram, hydrocarbon inclusions can be divided into five types: saturated hydrocarbon inclusion, less saturated hydrocarbon (oil or gas) inclusion,saturated hydrocarbon bitumen inclusion, bitumen inclusion, and methane water inclusion.

  5. Raman characteristics of hydrocarbon and hydrocarbon inclusions

    Institute of Scientific and Technical Information of China (English)


    The Raman spectrograms of hydrocarbon standard samples show that: (1) the Raman spectrogram of normal paraffin has very strong peaks of methyl and methylene (from 2700 cm-1 to 2970 cm-1); (2) branch methyl has the particular peak of 748 cm-1±; (3) six cyclic has the particular peak of 804 cm-1±; (4) phenyl has two particular peaks of 988 cm-1± and 3058 cm-1± and the 988 cm-1± peak is stronger than the 3058 cm-1± peak; and (5) hexene has three alkenyl spectrum peaks of 1294 cm-1±, 1635 cm-1± and 2996 cm-1±, with the 1635 cm-1± peak being the strongest, showing that the number of carbon in hy-drocarbon does not affect its Raman spectrogram, and the hydrocarbon molecular structure and base groups affect its Raman spectrogram, the same hydrocarbons (such as normal paraffin) have the same Raman spectrogram; the types (such as CH4, C2H6, C3H8) and the content of hydrocarbon in oil inclu-sions are not estimated by their characteristic Raman peaks. According to the Raman spectrograms of hydrocarbon compositions, the Raman spectrogram of hydrocarbon inclusion can be divided into five types: saturated hydrocarbon Raman spectrogram, fluoresce Raman spectrogram, saturated hydro-carbon bitumen Raman spectrogram, bitumen Raman spectrogram, and ethane Raman spectrogram. And according to the characteristics of Raman spectrogram, hydrocarbon inclusions can be divided into five types: saturated hydrocarbon inclusion, less saturated hydrocarbon (oil or gas) inclusion, saturated hydrocarbon bitumen inclusion, bitumen inclusion, and methane water inclusion.

  6. Geologic assessment of undiscovered oil and gas resources—Lower Cretaceous Albian to Upper Cretaceous Cenomanian carbonate rocks of the Fredericksburg and Washita Groups, United States Gulf of Mexico Coastal Plain and State Waters (United States)

    Swanson, Sharon M.; Enomoto, Catherine B.; Dennen, Kristin O.; Valentine, Brett J.; Cahan, Steven M.


    In 2010, the U.S. Geological Survey (USGS) assessed Lower Cretaceous Albian to Upper Cretaceous Cenomanian carbonate rocks of the Fredericksburg and Washita Groups and their equivalent units for technically recoverable, undiscovered hydrocarbon resources underlying onshore lands and State Waters of the Gulf Coast region of the United States. This assessment was based on a geologic model that incorporates the Upper Jurassic-Cretaceous-Tertiary Composite Total Petroleum System (TPS) of the Gulf of Mexico basin; the TPS was defined previously by the USGS assessment team in the assessment of undiscovered hydrocarbon resources in Tertiary strata of the Gulf Coast region in 2007. One conventional assessment unit (AU), which extends from south Texas to the Florida panhandle, was defined: the Fredericksburg-Buda Carbonate Platform-Reef Gas and Oil AU. The assessed stratigraphic interval includes the Edwards Limestone of the Fredericksburg Group and the Georgetown and Buda Limestones of the Washita Group. The following factors were evaluated to define the AU and estimate oil and gas resources: potential source rocks, hydrocarbon migration, reservoir porosity and permeability, traps and seals, structural features, paleoenvironments (back-reef lagoon, reef, and fore-reef environments), and the potential for water washing of hydrocarbons near outcrop areas.In Texas and Louisiana, the downdip boundary of the AU was defined as a line that extends 10 miles downdip of the Lower Cretaceous shelf margin to include potential reef-talus hydrocarbon reservoirs. In Mississippi, Alabama, and the panhandle area of Florida, where the Lower Cretaceous shelf margin extends offshore, the downdip boundary was defined by the offshore boundary of State Waters. Updip boundaries of the AU were drawn based on the updip extent of carbonate rocks within the assessed interval, the presence of basin-margin fault zones, and the presence of producing wells. Other factors evaluated were the middle

  7. Diagenesis Along Fractures in an Eolian Sandstone, Gale Crater, Mars (United States)

    Ming, D. W.; Yen, A. S.; Rampe, E. B.; Grotzinger, J. P.; Blake, D. F.; Bristow, T. F.; Chipera, S. J.; Downs, R.; Morris, R. V.; Morrison, S. M.; Vaniman, D. T.; Gellert, R.; Sutter, B.; Treiman, A. H.


    The Mars Science Laboratory rover Curiosity has been exploring sedimentary deposits in Gale crater since August 2012. The rover has traversed up section through approx.100 m of sedimentary rocks deposited in fluvial, deltaic, lacustrine, and eolian environments (Bradbury group and overlying Mount Sharp group). The Stimson formation lies unconformable over a lacustrine mudstone at the base of the Mount Sharp group and has been interpreted to be a cross-bedded sandstone of lithified eolian dunes. Mineralogy of the unaltered Stimson sandstone consists of plagioclase feldspar, pyroxenes, and magnetite with minor abundances of hematite, and Ca-sulfates (anhydrite, bassanite). Unaltered sandstone has a composition similar to the average Mars crustal composition. Alteration "halos" occur adjacent to fractures in the Stimson. Fluids passing through these fractures have altered the chemistry and mineralogy of the sandstone. Silicon and S enrichments and depletions in Al, Fe, Mg, Na, K, Ni and Mn suggest aqueous alteration in an open hydrologic system. Mineralogy of the altered Stimson is dominated by Ca-sulfates, Si-rich X-ray amorphous materials along with plagioclase feldspar, magnetite, and pyroxenes, but less abundant in the altered compared to the unaltered Stimson sandstone and lower pyroxene/plagioclase feldspar. The mineralogy and geochemistry of the altered sandstone suggest a complicated history with several (many?) episodes of aqueous alteration under a variety of environmental conditions (e.g., acidic, alkaline).

  8. Influence of deformation bands on sandstone porosity: A case study using three-dimensional microtomography (United States)

    Rodrigues, Mérolyn Camila Naves de Lima; Trzaskos, Barbara; Lopes, Angela Pacheco


    This study presents a qualitative and quantitative analysis of porosity in deformation bands by applying X-ray micro-computed tomography in conjunction with microstructural analysis. Samples of compactional cataclastic bands and shear compactional bands identified in Early Cretaceous aeolian sandstones of the Paraná Basin were analyzed. The application of X-ray micro-computed tomography expanded the view of features in the porous framework of each type of deformation band studied and provided information that are not clear or was not observable with optical microscopy. The compactional cataclastic bands and shear compactional bands differ in geometry, thickness, microstructures and, mainly, in the distribution, shape and orientation of the remaining pores. Porosity analysis was also performed by comparing values of porosity (total, open and closed pores) of the parental rock and the deformation band in each sample. Results of these analyses show a reduction of total porosity and open pores and therefore an increase in the amount of closed pores in all types of deformation bands in relation to parental rock. In addition, it is observed that changes in porosity characteristics are related to the effect of different deformation mechanisms that operated in each type of deformation band.

  9. Preliminary vitrinite and bitumen reflectance, total organic carbon, and pyrolysis data for samples from Upper and Lower Cretaceous strata, Maverick Basin, south Texas (United States)

    Hackley, Paul C.; Dennen, Kristin O.; Gesserman, Rachel M.; Ridgley, Jennie L.


    The Lower Cretaceous Pearsall Formation, a regionally occurring limestone and shale interval of 500-600-ft maximum thickness (Rose, 1986), is being evaluated as part of an ongoing U.S. Geological Survey (USGS) assessment of undiscovered hydrocarbon resources in onshore Lower Cretaceous strata of the northern Gulf of Mexico. The purpose of this report is to release preliminary vitrinite and bitumen reflectance, total organic carbon, and pyrolysis data for Pearsall Formation, Glen Rose Formation, Hosston Formation, Austin Group, and Eagle Ford Group samples from the Maverick Basin in south Texas in order to aid in the characterization of these strata in this area. The preliminary nature of this report and the data contained herein reflect that the assessment and characterization of these samples is a work currently in progress. Pearsall Formation subdivisions are, in ascending stratigraphic order, the Pine Island Shale, James Limestone, and Bexar Shale Members (Loucks, 2002). The Lower Cretaceous Glen Rose Formation is also part of the USGS Lower Cretaceous assessment and produces oil in the Maverick Basin (Loucks and Kerans, 2003). The Hosston Formation was assessed by the USGS for undiscovered oil and gas resources in 2006 (Dyman and Condon, 2006), but not in south Texas. The Upper Cretaceous Austin Group is being assessed as part of the USGS assessment of undiscovered hydrocarbon resources in the Upper Cretaceous strata of the northern Gulf of Mexico and, along with the Upper Cretaceous Eagle Ford Group, is considered to be an important source rock in the Smackover-Austin-Eagleford Total Petroleum System (Condon and Dyman, 2006). Both the Austin Group and the Eagle Ford Group are present in the Maverick Basin in south Texas (Rose, 1986).

  10. 3D seismic analysis of the Collyhurst Sandstone: implications for CO2 sequestration in the East Irish Sea Basin (United States)

    Gamboa, Davide; Williams, John; Kirk, Karen; Gent, Christopher; Bentham, Michelle; Fellgett, Mark; Schofield, David


    Carbon Capture and Storage (CCS) is a vital technology towards low-carbon energy resources and the mitigation of global warming trends induced by rising CO2 levels in the atmosphere. The East Irish Sea Basin (EISB) is a key area for CCS in the western UK, having high CO2 storage potentials in explored hydrocarbon fields and in saline aquifers within the Permo-Triassic Sherwood Sandstone Formation. However, the theoretical storage potential of the EISB could be poorly estimated as the reservoir-prone Lower Permian formations are not considered in detail by current estimations. This work aims to fill this gap, focusing on the characterisation of the Lower Permian Collyhurst Sandstone Formation as a viable storage unit. The potential for CO2 storage is estimated as the total volume/area of suitable closures that are isolated by structural traps, occurring at depths suitable for CO2 injection and containment (>800m). Detailed structural and stratigraphic interpretations were made using 3D seismic data to assess the storage potential of the Collyhurst Sandstone Formation in the southern EISB. The basin strata is compartmentalised by numerous N-S trending faults. A higher degree of compartmentalisation occurs within regional anticlines where elongated tilted blocks are observed, bound by predominantly west-dipping faults that induce a variable offset of the Collyhurst Sandstone strata. Contrastingly, higher lateral continuity of this formation is observed within graben basins were faults are less frequent and with minor offset, thus potentially creating larger storage closures. Fault dip orientation in the grabens is variable, with west and east dipping faults occurring as a function of large east-dipping listric faults. This study was complemented by the stress modelling of the interpreted faults in order to assess the risk of CO2 leakage. Analysis of borehole breakouts observed in four approximately vertical wells in the EISB suggest a maximum horizontal stress

  11. Sedimentary record of terminal Cretaceous accretions in Ecuador: The Yunguilla Group in the Cuenca area (United States)

    Jaillard, Etienne; Bengtson, Peter; Ordoñez, Martha; Vaca, Wilmer; Dhondt, Annie; Suárez, Johnny; Toro, Jorge


    A reappraisal of the "Late Cretaceous Yunguilla Formation" of the Cuenca area enables the definition of four distinct formations, correlatable with those of southwestern Ecuador. A mid- to late-Campanian marine transgression (Jadán Formation) is overlain by quartz-rich conglomerates of fan-delta to turbiditic fan environment (Quimas Formation) of latest Campanian-earliest Maastrichtian age, which are interpreted as evidence of the accretion of a first oceanic terrane (San Juan). Disconformable, arkosic turbidites and cherts (Tabacay Formation) of early Maastrichtian age are thought to represent the erosion of the newly accreted oceanic terrane. A major unconformity of late Maastrichtian age, caused by the accretion of a second oceanic terrane (Guaranda), is followed by the deposition of quartz-rich micaceous shelf sandstones (Saquisilí Formation) of Paleocene age. A third accretion event (late Paleocene) is recorded in coastal Ecuador. Each accretion event correlates with the uplift and erosion of the Eastern Cordillera and with a sedimentary hiatus in the eastern areas. In Ecuador, accretion of oceanic terranes contributed to the build up of the Andes through tectonic underplating of low-density material, and the eastern areas did not behave as flexural foreland basins during late Cretaceous-Paleogene times.

  12. Dinosaur footprints and other ichnofauna from the cretaceous Kem Kem beds of Morocco. (United States)

    Ibrahim, Nizar; Varricchio, David J; Sereno, Paul C; Wilson, Jeffery A; Wilson, Jeff A; Dutheil, Didier B; Martill, David M; Baidder, Lahssen; Zouhri, Samir


    We describe an extensive ichnofossil assemblage from the likely Cenomanian-age 'lower' and 'upper' units of the 'Kem Kem beds' in southeastern Morocco. In the lower unit, trace fossils include narrow vertical burrows in cross-bedded sandstones and borings in dinosaur bone, with the latter identified as the insect ichnotaxon Cubiculum ornatus. In the upper unit, several horizons preserve abundant footprints from theropod dinosaurs. Sauropod and ornithischian footprints are much rarer, similar to the record for fossil bone and teeth in the Kem Kem assemblage. The upper unit also preserves a variety of invertebrate traces including Conichnus (the resting trace of a sea-anemone), Scolicia (a gastropod trace), Beaconites (a probable annelid burrow), and subvertical burrows likely created by crabs for residence and detrital feeding on a tidal flat. The ichnofossil assemblage from the Upper Cretaceous Kem Kem beds contributes evidence for a transition from predominantly terrestrial to marine deposition. Body fossil and ichnofossil records together provide a detailed view of faunal diversity and local conditions within a fluvial and deltaic depositional setting on the northwestern coast of Africa toward the end of the Cretaceous.

  13. Dinosaur footprints and other ichnofauna from the cretaceous Kem Kem beds of Morocco.

    Directory of Open Access Journals (Sweden)

    Nizar Ibrahim

    Full Text Available We describe an extensive ichnofossil assemblage from the likely Cenomanian-age 'lower' and 'upper' units of the 'Kem Kem beds' in southeastern Morocco. In the lower unit, trace fossils include narrow vertical burrows in cross-bedded sandstones and borings in dinosaur bone, with the latter identified as the insect ichnotaxon Cubiculum ornatus. In the upper unit, several horizons preserve abundant footprints from theropod dinosaurs. Sauropod and ornithischian footprints are much rarer, similar to the record for fossil bone and teeth in the Kem Kem assemblage. The upper unit also preserves a variety of invertebrate traces including Conichnus (the resting trace of a sea-anemone, Scolicia (a gastropod trace, Beaconites (a probable annelid burrow, and subvertical burrows likely created by crabs for residence and detrital feeding on a tidal flat. The ichnofossil assemblage from the Upper Cretaceous Kem Kem beds contributes evidence for a transition from predominantly terrestrial to marine deposition. Body fossil and ichnofossil records together provide a detailed view of faunal diversity and local conditions within a fluvial and deltaic depositional setting on the northwestern coast of Africa toward the end of the Cretaceous.

  14. The Petrology and Diagenetic History of the Phacoides Sandstone, Temblor Formation at the McKittrick Oil Field, California (United States)

    Kaess, A. B.; Horton, R. A.


    The McKittrick oil field is located near the western edge of the San Joaquin Basin, California. The oil field is currently in production with 480 wells producing from the Tulare, San Joaquin, Reef Ridge, Monterey, Temblor, Tumey, and Kreyenhagen formations. Within the Temblor Formation production is mainly from the Miocene Carneros and the Phacoides sandstones. Eighty-two samples from the Phacoides sandstone (2403 - 3045 m below surface) were obtained from the California Well Sample Repository to characterize and understand the diagenetic history and its influence on its reservoir properties. Petrographic thin sections were analyzed by quantitative optical petrography, energy dispersive X-ray spectrometry, and imaging with back-scatter electron and cathodoluminescence. The Phacoides sandstone consists of fine to very coarse, poorly to well-sorted, arkosic arenites, and wackes with detrital framework grains including sub-angular quartz, K-feldspar (microcline and orthoclase), plagioclase, and lithic fragments. Ba-free, Ba-rich, and perthitic K-feldspars are present. Accessory minerals include glauconite, biotite, muscovite, magnetite, titanomagnetite, sphene, zircon, apatite, corundum, and rutile. Diagenetic alteration includes: (1) compaction, (2) mineral dissolution, (3) albitization of feldspars, alteration of biotite to pyrite and chlorite, replacement of framework grains by calcite, (4) alteration of volcanic rock fragments, (5) cementation by kaolinite, calcite and dolomite, and (6) precipitation of K-feldspar and quartz overgrowths. Early-formed fractures were healed by authigenic quartz, albite, and K-feldspars. Precipitation of carbonates and clays, rearranging of broken grains, and formation of pseudomatrix reduced primary porosity. Secondary porosity is common and formed initially by the dissolution of plagioclase (excluding albite) and volcanic fragments, and later by dissolution of calcite, dolomite, and detrital K-feldspars. Hydrocarbon emplacement was

  15. Dynamic triggering during rupture nucleation in sandstone (United States)

    Schubnel, Alexandre; Chanard, Kristel; Latour, Soumaya; Petrelis, François; Hatano, Takahiro; Mair, Karen; Vinciguerra, Sergio


    Fluid induced stress perturbations in the crust at seismogenic depths can be caused by various sources, such as deglaciation unloading, magmatic intrusion or fluid injection and withdrawal. Numbers of studies have robustly shown their link to earthquake triggering. However, the role of small periodic stress variations induced by solid earth and oceanic tides or seasonal hydrology in the seismic cycle, of the order of a few kPa, remains unclear. Indeed, the existence or absence of correlation between these loading phenomena and earthquakes have been equally proposed in the literature. To investigate this question, we performed a set of triaxial deformation experiments on porous water-saturated Fontainebleau sandstones. Rock samples were loaded by the combined action of steps of constant stress (creep), intended to simulate tectonic loading and small sinusoidal pore pressure variations with a range of amplitudes, analogous to tides or seasonal loading. All tests were conducted at a regulated temperature of 35C and a constant 35 MPa confining pressure. Our experimental results show that (1) pore pressure oscillations do not seem to influence the deformation rate at which the rock fails, (2) they correlate with acoustic emissions. Even more interestingly, we observe a progressive increase of the correlation coefficient in time as the rock approaches failure. The correlation coefficient is also sensitive to the amplitude of pore pressure oscillations as larger oscillations produce higher correlation levels. Finally, we show that, in the last hours of creep before failure, acoustic emissions occur significantly more when the pore pressure is at its lowest. This suggest that the correlation of small stress perturbations and acoustic emissions depend on the state stress of a rock and the amplitude of the perturbations and that emissions occur more likely when cracks are unclamped.

  16. Chapter 2. Assessment of undiscovered conventional oil and gas resources--Upper Jurassic-Lower Cretaceous Cotton Valley group, Jurassic Smackover interior salt basins total petroleum system, in the East Texas basin and Louisiana-Mississippi salt basins provinces. (United States)

    Dyman, T.S.; Condon, S.M.


    The Jurassic Smackover Interior Salt Basins Total Petroleum System is defined for this assessment to include (1) Upper Jurassic Smackover Formation carbonates and calcareous shales and (2) Upper Jurassic and Lower Cretaceous Cotton Valley Group organic-rich shales. The Jurassic Smackover Interior Salt Basins Total Petroleum System includes four conventional Cotton Valley assessment units: Cotton Valley Blanket Sandstone Gas (AU 50490201), Cotton Valley Massive Sandstone Gas (AU 50490202), Cotton Valley Updip Oil and Gas (AU 50490203), and Cotton Valley Hypothetical Updip Oil (AU 50490204). Together, these four assessment units are estimated to contain a mean undiscovered conventional resource of 29.81 million barrels of oil, 605.03 billion cubic feet of gas, and 19.00 million barrels of natural gas liquids. The Cotton Valley Group represents the first major influx of clastic sediment into the ancestral Gulf of Mexico. Major depocenters were located in south-central Mississippi, along the Louisiana-Mississippi border, and in northeast Texas. Reservoir properties and production characteristics were used to identify two Cotton Valley Group sandstone trends across northern Louisiana and east Texas: a high-permeability blanket-sandstone trend and a downdip, low-permeability massive-sandstone trend. Pressure gradients throughout most of both trends are normal, which is characteristic of conventional rather than continuous basin-center gas accumulations. Indications that accumulations in this trend are conventional rather than continuous include (1) gas-water contacts in at least seven fields across the blanket-sandstone trend, (2) relatively high reservoir permeabilities, and (3) high gas-production rates without fracture stimulation. Permeability is sufficiently low in the massive-sandstone trend that gas-water transition zones are vertically extensive and gas-water contacts are poorly defined. The interpreted presence of gas-water contacts within the Cotton Valley

  17. Sedimentary and tectonic evolution of the arc zone of Southwestern Ecuador during Late Cretaceous and early Tertiary times (United States)

    Jaillard, Etienne; Ordoñez, Martha; Berrones, Gerardo; Bengtson, Peter; Bonhomme, Michel; Jimenez, Nelson; Zambrano, Italo


    The eastern part of the "Celica basin" of southwesternmost Ecuador exhibits Late Cretaceous to Tertiary sediments which belong to the magmatic arc paleogeographic zone. Important N-S to NE-trending faults separate a western, mainly Late Cretaceous series (Río Playas) from an eastern succession (Catamayo-Gonzanamá) of (?) Late Cretaceous to early Tertiary age. The analysis of these sediments indicates a complex geologic history, which recorded the main stages of the early tectonic evolution of the Andes. In the Río Playas area, a submarine andesitic volcanic pile (Celica Fm) represents the products of a volcanic arc of probably Albian age. It is apparently overlain by a thick, early Late Cretaceous series of volcanic flows and coarse-grained volcaniclastic high-density turbiditic beds (Alamor Fm), the deposition of which might result from the Mochica phase (late Albian-early Cenomanian) Deformation, uplift and erosion (early Peruvian phase) are followed by the sedimentation of unconformable marls and greywackes of marine open shelf to deltaic environment. These comprise Santonian and/or Campanian fine- to mediumgrained deposits (Naranjo Fm), abruptly overlain (late Peruvian phase ?) by fan-delta coarse-grained marine deposits of latest Cretaceous age (Casanga Fm) They are locally capped by undated, partly volcaniclastic red beds, indicating an important regression/uplift of latest Cretaceous-early Tertiary age. In the Catamayo-Gonzanamá area, thick subaerial andesitic volcanic rocks (Sacapalca Fm) are intruded by Paleocene to early Eocene plutons and are overlain by undated fluvial red beds. They express uplift movements of latest Cretaceous-early Tertiary age. To the South, these are capped by slumped lacustrine black shales and greywackes of possible Maastrichtian-Paleocene age (Gonzanamá Fm) Farther north, the Sacapalca volcanics and red beds are overlain by variegated shales, sandstones and conglomerates, dated as latest Oligocene-early Miocene (Catamayo Fm

  18. Lower Cretaceous Dinosaur Tracks from Puebla, Mexico

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    Rubén A. Rodríguez-de la Rosa


    Full Text Available Dinosaur tracks have been identified near San Martín Atexcal, southern Puebla, Mexico, within the sedimentary sequence of the San Juan Raya Formation of Lower Cretaceous (Albian age. The tracksite, located in the bed of the Magdalena River, reveals six different ichnofossiliferous levels identified within a 9 m thick sedimentary sequence. The inferred environment is that of a tidal (marginal marine mudflat (Level I. Level I preserves three theropods trackways (?Allosauroidea, additionally, isolated tracks belonging to iguanodontids (Ornithopoda. Level II preserves faint iguanodontid tracks. Levels III to V preserve sauropod tracks. Younger level VI preserves, although morphologically different, a track belonging to Ornithopoda. The dinosaur tracks from San Martín Atexcal support the existence of continental facies within the San Juan Raya Formation; they represent the second record of dinosaur tracks from the Lower Cretaceous of Mexico and are part of an important but little documented record of Lower Cretaceous dinosaurs in Mexico.

  19. Tectonic evolution of the Malay Peninsula inferred from Jurassic to Cretaceous paleomagnetic results (United States)

    Otofuji, Yo-ichiro; Moriyama, Yuji T.; Arita, Maiko P.; Miyazaki, Masanari; Tsumura, Kosuke; Yoshimura, Yutaka; Shuib, Mustaffa Kamal; Sone, Masatoshi; Miki, Masako; Uno, Koji; Wada, Yutaka; Zaman, Haider


    A primary remanent magnetization is identified in the Jurassic-Cretaceous red bed sandstones of the Tembeling Group in Peninsular Malaysia. This high-temperature magnetic component is unblocked at 680-690 °C, revealing a clockwise deflected direction of Ds = 56.8°, Is = 31.6° (where ks = 8.5, α95 = 11.3° and N = 22) in stratigraphic coordinates. The primary origin of this component is ascertained by a positive fold test and a geomagnetic polarity reversal in the Kuala Wau section. Secondary remanent magnetizations are identified in the rocks of the Tembeling and Bertangga basins, which indicate a counter-clockwise deflection in the geographic coordinates (Dg = 349.1°, Ig = 15.3° where kg = 11.8, α95 = 5.1°, N = 72). The comparison with the expected paleomagnetic directions from the 130 Ma and 40 Ma Eurasian poles indicates two-stages of tectonic movement in the southern Malay Peninsula: (1) a clockwise rotation of 61.1° ± 11.9° accompanied by a 13.3° ± 8.1° southward displacement after the Cretaceous; and (2) a subsequent counter-clockwise rotation of 18.5° ± 5.0° to the present day position. The first stage of rotation is ascribed to tectonic deformation caused by the indentation of India into Asia after 55 Ma, while the second stage is attributed to the collision of the Australian Plate with SE Asia after 30-20 Ma. The present paleomagnetic results from the Jurassic-Cretaceous Tembeling Group thus reveal impacts of both of these collisions on SE Asia in general and on Peninsular Malaysia in particular.

  20. Sandstone Diagenesis at Gale Crater, Mars, As Observed By Curiosity (United States)

    Siebach, K. L.; Grotzinger, J. P.; McLennan, S. M.; Hurowitz, J.; Kah, L. C.; Edgett, K. S.; Williams, R. M. E.; Wiens, R. C.; Schieber, J.


    The Mars Science Laboratory rover, Curiosity, has encountered a significant number of poorly-sorted and very well-lithified sandstones along its traverse on the floor of Gale Crater. We use images from the hand-lens imager (MAHLI) and elemental chemistry from the ChemCam laser-induced breakdown spectroscopy instrument (LIBS) and the alpha-particle x-ray spectrometer (APXS) to begin to constrain the diagenetic history of these sandstones, including lithification and possible later dissolution. Investigation of MAHLI images reveals that the sediments are poorly-sorted and show very low apparent porosity, generally less than ~5%. However, in some cases, such as the Gillespie Lake sandstone identified in Yellowknife Bay, this apparent porosity includes a significant fraction of void spaces larger than typical sediment grain sizes (~30% by number or 75% of void spaces by area). One possible explanation of these larger pits is that they represent recent removal of soft intraclasts by eolian abrasion. Another possibility is that later diagenetic fluids caused dissolution of more soluble grains, and production of secondary porosity. Investigation into the elemental chemistry of the sandstones has shown that they have a relatively unaltered basaltic bulk composition in spite of possessing a variety of secondary minerals and amorphous material, indicating isochemical diagenetic processes. The chemistry and mineralogy of the cement is not immediately evident based on the initial analyses; there is not a high percentage of salts or evaporative minerals that may easily cement near-surface sandstones. Furthermore, these sandstones lack textures and compositions consistent with pedogenic processes, such as calcrete, silcrete, or ferricrete. Instead, they may record burial and cementation at depth. Cement composition may be constrained through comparison to terrestrial basaltic sandstones, and studying chemical variations along ChemCam and APXS transects of the rocks.

  1. Geology of the Lower Cretaceous Travis Peak Formation, East Texas. Depositional history, diagenesis, structure, and reservoir-engineering implications. Topical report, November 1982-February 1990

    Energy Technology Data Exchange (ETDEWEB)

    Dutton, S.P.; Laubach, S.E.; Tye, R.S.; Baumgardner, R.W.; Herrington, K.L.


    The report summarizes stratigraphic, petrographic, and structural studies of the Lower Cretaceous Travis Peak Formation, a low-permeability gas sandstone in East Texas, and presents reservoir engineering implications. Depositional systems in this region were interpreted from logs and cores and include (1) a braided- to meandering-fluvial system that forms the majority of the Travis Peak section; (2) deltaic deposits interbedded with the distal part of the fluvial system; (3) paralic deposits that overlie and interfinger with the deltaic and fluvial deposits near the top of the Travis Peak; and (4) shelf deposits present at the downdip extent of the formation. Petrographic studies indicate the sandstones are quartzarenites and subarkoses. Cementation by quartz, dolomite, ankerite, illite, chlorite, and reservoir bitumen have reduced porosity to less than 8 percent and permeability to less than 0.1 md throughout most of the formation. Structurally deeper sandstones are more intensely quartz cemented than are shallower sandstones and contain abundant, open natural fractures. Borehole breakouts and drilling-induced fractures in core can be used to predict horizontal stress directions and the direction of hydraulic fracture propagation. Hydraulic fractures propagate in directions subparallel to the east-northeast strike of the natural fractures; thus, hydraulically induced fractures may not intersect many natural fractures.

  2. Ground-based Hyperspectral Remote Sensing for Mapping Rock Alterations and Lithologies: Case Studies from Semail Ophiolite, Oman and Rush Springs Sandstone, Oklahoma (United States)

    Sun, L.; Khan, S.; Hauser, D. L.; Glennie, C. L.; Snyder, C.; Okyay, U.


    This study used ground-based hyperspectral remote sensing data to map rock alterations and lithologies at Semail Ophiolite, Oman, as well as hydrocarbon-induced rock alterations at Cement, Oklahoma. The Samail Ophiolite exposed the largest, least-deformed, and the most-studied ophiolite in the world. Hydrocarbon seepages at Cement, Oklahoma brought hydrocarbons to the Rush Springs sandstones at surface, and generated rock alterations including bleaching of red beds, and carbonate cementation. Surficial expressions of rock alterations and different lithofacies are distinct from adjacent rocks, and can be detected by remote sensing techniques. Hyperspectral remote sensing acquires light intensity for hundreds of bands in a continuous electromagnetic spectrum from visible light to short-wave infrared radiation, and holds potential to characterize rocks with great precision. Ground-based hyperspectral study could scan the objects at close ranges thus provide very fine spatial resolutions (millimeters to centimeters). This study mapped all the major iconic outcrops of Semail ophiolite including pillow lava, sheeted dykes, layered gabbros, and peridotites. This study also identified surficial rock alterations induced by hydrocarbons at Cement, Oklahoma. Reddish-brown Rush Spring sandstones are bleached to pink, yellow, and gray colors; pore spaces in the sandstones have been filled with carbonate cementation. Laboratory spectroscopy was used to assist with mineral identification and classification in hyperspectral data. Terrestrial laser scanning (TLS) was used to provide high-accuracy spatial references. Principal component analysis, minimum noise fraction, spectral angle mapper, and band ratios are used in image processing. Combining lithological, remote sensing and geochemical data, this study built a model for petroleum seepage and related rock alterations, and provided a workflow for employing ground-based hyperspectral remote sensing techniques in petrological

  3. Late Cretaceous vicariance in Gondwanan amphibians.

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    Ines Van Bocxlaer

    Full Text Available Overseas dispersals are often invoked when Southern Hemisphere terrestrial and freshwater organism phylogenies do not fit the sequence or timing of Gondwana fragmentation. We used dispersal-vicariance analyses and molecular timetrees to show that two species-rich frog groups, Microhylidae and Natatanura, display congruent patterns of spatial and temporal diversification among Gondwanan plates in the Late Cretaceous, long after the presumed major tectonic break-up events. Because amphibians are notoriously salt-intolerant, these analogies are best explained by simultaneous vicariance, rather than by oceanic dispersal. Hence our results imply Late Cretaceous connections between most adjacent Gondwanan landmasses, an essential concept for biogeographic and palaeomap reconstructions.

  4. Astronomical calibration of the Maastrichtian (Late Cretaceous)

    DEFF Research Database (Denmark)

    Husson, Dorothée; Galbrun, Bruno; Laskar, Jacques;


    Recent improvements to astronomical modeling of the Solar System have contributed to important refinements of the Cenozoic time scale through astronomical calibration of sedimentary series. We extend this astronomical calibration into the Cretaceous, on the base of the 405 ka orbital eccentricity......, with the presence of cycles corresponding to forcing by precession, obliquity and orbital eccentricity variations. Identification of these cycles leads to the definition of a detailed cyclostratigraphic frame covering nearly 8 Ma, from the upper Campanian to the Cretaceous/Paleogene (K/Pg) boundary. Durations...

  5. Cretaceous shallow drilling, US Western Interior: Core research. Technical progress report

    Energy Technology Data Exchange (ETDEWEB)

    Arthur, M.A.


    This project is a continuing multidisciplinary study of middle to Upper Cretaceous marine carbonate and clastic rocks in the Utah-Colorado-Kansas corridor of the old Cretaceous seaway that extended from the Gulf Coast to the Arctic during maximum Cretaceous transgressions. It is collaborative between in the US Geological Survey (W.E. Dean, P.I.) and University researchers led by The Pennsylvania State University(M.A. Arthur, P.I.) and funded by DOE and the USGS, in part. Research focusses on the Greenhom, Niobrara and lower Pierre Shale units and their equivalents, combining biostratigraphic/paleoecologic studies, inorganic, organic and stable isotopic geochemical studies, mineralogical investigations and high-resolution geophysical logging. This research requires unweathered samples and continuous smooth ``exposures`` in the form of cores from at least 4 relatively shallow reference holes (i.e. < 1000m) in transect from east to west across the basin. The major initial effort was recovery in Year 1 of the project of continuous cores from each site in the transect. This drilling provided samples and logs of strata ranging from pelagic sequences that contain organic-carbon-rich marine source rocks to nearshore coal-bearing units. This transect also will provide information on the extent of thermal maturation and migration of hydrocarbons in organic-carbon-rich strata along a burial gradient.

  6. Micropaleontology and palaeoclimate during the early Cretaceous in the Lishu depression, Songliao basin, Northeast China

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    Wei Yan


    Full Text Available Diverse and abundant microfossils, such as palynomorphs, algae and Ostracoda, were collected from lower Cretaceous strata of Lishu depression, located in southeastern Songliao basin, and were identified and classified in order to provide relevant, detailed records for paleoclimate research. The early Cretaceous vegetation and climate of southeastern Songliao basin have been inferred from the analysis of palynomorph genera, algae and Ostracoda of the LS1 and SW110 wells. The lower Cretaceous strata include, in ascending stratigraphic order, the Shahezi, Yingcheng and Denglouku formations. Palynological assemblages for each formation, based on biostratigraphic and statistical analyses, provide an assessment of their longitudinal variations. During deposition of the Shahezi Formation, the climate was mid-subtropical. Vegetation consisted of coniferous forest and herbage. During deposition of the Yingcheng Formation, the climate was south Asian tropical. Vegetation consisted mainly of coniferous forest and herbal shrub. In addition, fresh and saline non-marine water dominated the lacustrine setting during deposition of these formations. Deposition of the Denglouku Formation, however, occurred under a hot and dry tropical climate. The vegetation was mostly coniferous forest and lake waters became saline. Palaeoclimate variation is correlated by the lake level change and the development of sedimentary facies. Palaeoclimate contribute to the formation of hydrocarbon source rocks and reservoir.

  7. Erosion characteristic of slope sandstone soaking in acid mine drainage

    Institute of Scientific and Technical Information of China (English)

    JIANG Li-chun; CHEN Jia-sheng; WU Ai-xiang


    Acid mine drainage(AMD) is one of the main reasons of slope instability in chemical mines with high sulfide. The pH values of the solution inside the mining pit decrease with the increasing of distance from ore body and vary from 1.2 to 4.6,according to the results of the water environmental investigation and the composition test of the slope sandstone in Xinqiao Pyrite Mine. Comparative experiments between original sandstone and AMD eroded sandstone samples show that after AMD erosion the uniaxial compressive strength and elastic modulus decrease by 30%-50% and 25%-45%, respectively, the cohesion and internal friction angle decrease obviously, and the Poisson ratio fluctuates between 0.20-0.29. The greater joints development, the higher residual stress after peak value, and the longer time to damage. Besides above, the reaction mechanism analysis of AMD eroded sandstone shows that the fillings in joints and fissures of sandstone are frequently decomposed and polyreacted, resulting in changes of interior molecule structure and framework composition, and decreases of cohesion and angle of internal friction between rock structure interfaces.

  8. Ferroan dolomite cement in Cambrian sandstones: burial history and hydrocarbon generation of the Baltic sedimentary basin

    DEFF Research Database (Denmark)

    Sliaupa, S.; Cyziene, J.; Molenaar, Nicolaas


    . The burial history modelling points to development of most of the dolomite cement during rapid Silurian-Devonian subsidence and Carboniferous-early Permian uplift. A wide range of precipitation temperatures indicate that temperature was not a major factor in triggering the carbonate cementation. Dolomite...... precipitation is related to early stages of organic matter maturation and thus to the oil generation history in the basin. delta C-13 values vary from +0.03% to -6.2%( PDB), suggesting limited addition of carbon from an organic source, with the major part derived from marine bicarbonate. The sourcing of carbon...

  9. Total petroleum systems of the Pelagian Province, Tunisia, Libya, Italy, and Malta; the Bou Dabbous, Tertiary and Jurassic-Cretaceous composite (United States)

    Klett, T.R.


    Undiscovered conventional oil and gas resources were assessed within total petroleum systems of the Pelagian Province (2048) as part of the U.S. Geological Survey World Petroleum Assessment 2000. The Pelagian Province is located mainly in eastern Tunisia and northwestern Libya. Small portions of the province extend into Malta and offshore Italy. Although several petroleum systems may exist, only two ?composite? total petroleum systems were identified. Each total petroleum system comprises a single assessment unit. These total petroleum systems are called the Bou Dabbous?Tertiary and Jurassic-Cretaceous Composite, named after the source-rock intervals and reservoir-rock ages. The main source rocks include mudstone of the Eocene Bou Dabbous Formation; Cretaceous Bahloul, Lower Fahdene, and M?Cherga Formations; and Jurassic Nara Formation. Known reservoirs are in carbonate rocks and sandstone intervals throughout the Upper Jurassic, Cretaceous, and Tertiary sections. Traps for known accumulations include fault blocks, low-amplitude anticlines, high-amplitude anticlines associated with reverse faults, wrench fault structures, and stratigraphic traps. The estimated means of the undiscovered conventional petroleum volumes in total petroleum systems of the Pelagian Province are as follows: [MMBO, million barrels of oil; BCFG, billion cubic feet of gas; MMBNGL, million barrels of natural gas liquids] Total Petroleum System MMBO BCFG MMBNGL Bou Dabbous?Tertiary 667 2,746 64 Jurassic-Cretaceous Composite 403 2,280 27

  10. Proximal impact deposits at the Cretaceous-Tertiary boundary in the Gulf of Mexico: A restudy of DSDP Leg 77 Sites 536 and 540

    Energy Technology Data Exchange (ETDEWEB)

    Alvarez, W.; Asaro, F. (Univ. of California, Berkeley (United States)); Smit, J. (Free Univ. of Amsterdam (Netherlands)); Lowrie, W. (Inst. fuer Geophysik, Zuerich (Switzerland)); Asaro, F. (Lawrence Berkeley Lab., CA (United States)); Margolis, S.V.; Claeys, P. (Univ. of California, Davis (United States)); Kastner, M. (Univ. of California, San Diego (United States)); Hildebrand, A.R. (Geological Survey, Ottawa, Ontario (Canada))


    Restudy of Deep Sea Drilling Project Sites 536 and 540 in the southeast Gulf of Mexico gives evidence for a giant wave at Cretaceous-Tertiary boundary time. Five units are recognized: (1) Cenomanian limestone underlies a hiatus in which the five highest Cretaceous stages are missing, possibly because of catastrophic K-T erosion. (2) Pebbly mudstone, 45 m thick, represents a submarine landslide possibly of K-T age. (3) Current-bedded sandstone, more than 2.5 m thick, contains anomalous iridium, tektite glass, and shocked quartz; it is interpreted as ejecta from a nearby impact crater, reworked on the deep-sea floor by the resulting tsunami. (4) A 50-cm interval of calcareous mudstone containing small Cretaceous planktic foraminifera and the Ir peak is interpreted as the silt-size fraction of the Cretaceous material suspended by the impact-generated wave. (5) Calcareous mudstone with basal Tertiary forams and the uppermost tail of the Ir anomaly overlies the disturbed interval, dating the impact and wave event as K-T boundary age. Like Beloc in Haiti and Mimbral in Mexico, Sites 536 and 540 are consistent with a large K-T age impact at the nearby Chicxulub crater.

  11. Sandstone provenance and tectonic evolution of the Xiukang Mélange from Neotethyan subduction to India-Asia collision (Yarlung-Zangbo suture, south Tibet) (United States)

    An, Wei; Hu, Xiumian; Garzanti, Eduardo


    The Xiukang Mélange of the Yarlung-Zangbo suture zone in south Tibet documents low efficiency of accretion along the southern active margin of Asia during Cretaceous Neotethyan subduction, followed by final development during the early Paleogene stages of the India-Asia collision. Here we investigate four transverses in the Xigaze area (Jiding, Cuola Pass, Riwuqi and Saga), inquiry the composition in each transverse, and present integrated petrologic, U-Pb detrital-zircon geochronology and Hf isotope data on sandstone blocks. In fault contact with the Yarlung-Zangbo Ophiolite to the north and the Tethyan Himalaya to the south, the Xiukang mélange can be divided into three types: serpentinite-matrix mélange composed by broken Yarlung-Zangbo Ophiolite, thrust-sheets consisting mainly chert, quartzose or limestone sheets(>100m) with little intervening marix, and mudstone-matrix mélange displaying typical blocks-in-matrix texture. While serpentinite-matrix mélange is exposed adjacent to the ophiolite, distributions of thrust-sheets and blocks in mudstone-matrix mélange show along-strike diversities. For example, Jiding transverse is dominant by chert sheets and basalt blocks with scarcely sandstone blocks, while Cuola Pass and Saga transverses expose large amounts of limestone/quartzarenite sheets in the north and volcaniclastic blocks in the south. However, turbidite sheets and volcaniclastic blocks are outcropped in the north Riwuqi transverse with quartzarenite blocks preserved in the south. Three groups of sandstone blocks/sheets with different provenance and depositional setting are distinguished by their petrographic, geochronological and isotopic fingerprints. Sheets of turbiditic quartzarenite originally sourced from the Indian continent were deposited in pre-Cretaceous time on the northernmost edge of the Indian passive margin and eventually involved into the mélange at the early stage of the India-Asia collision. Two distinct groups of volcaniclastic-sandstone

  12. Optical coherence tomography for vulnerability assessment of sandstone. (United States)

    Bemand, Elizabeth; Liang, Haida


    Sandstone is an important cultural heritage material, in both architectural and natural settings, such as neolithic rock art panels. The majority of deterioration effects in porous materials such as sandstone are influenced by the presence and movement of water through the material. The presence of water within the porous network of a material results in changes in the optical coherence tomography signal intensity that can be used to monitor the wetting front of water penetration of dry porous materials at various depths. The technique is able to detect wetting front velocities from 1 cm s(-1) to 10(-6) cm s(-1), covering the full range of hydraulic conductivities likely to occur in natural sandstones from pervious to impervious.

  13. Diagenetic effect on permeabilities of geothermal sandstone reservoirs

    DEFF Research Database (Denmark)

    Weibel, Rikke; Olivarius, Mette; Kristensen, Lars

    The Danish subsurface contains abundant sedimentary deposits, which can be utilized for geothermal heating. The Upper Triassic – Lower Jurassic continental-marine sandstones of the Gassum Formation has been utilised as a geothermal reservoir for the Thisted Geothermal Plant since 1984 extracting...... and permeability is caused by increased diagenetic changes of the sandstones due to increased burial depth and temperatures. Therefore, the highest water temperatures typically correspond with the lowest porosities and permeabilities. Especially the permeability is crucial for the performance of the geothermal......-line fractures. Continuous thin chlorite coatings results in less porosity- and permeability-reduction with burial than the general reduction with burial, unless carbonate cemented. Therefore, localities of sandstones characterized by these continuous chlorite coatings may represent fine geothermal reservoirs...

  14. Hydrocarbon Potential of Pre-cenozoic Strata in the North Yellow Sea Basin

    Institute of Scientific and Technical Information of China (English)

    CAI Feng; DAI Chunshan; CHEN Jianwen; LI Gang; SUN Ping


    The North Yellow Sea Basin ( NYSB ), which was developed on the basement of North China (Huabei) continental block, is a typical continental Mesozoic-Cenozoic sedimentary basin in the sea area. Its Mesozoic basin is a residual basin,below which there is probably a larger Paleozoic sedimentary basin. The North Yellow Sea Basin comprises four sags and three uplifts. Of them, the eastern sag is a Mesozoic-Cenozoic sedimentary sag in NYSB and has the biggest sediment thickness; the current Korean drilling wells are concentrated in the eastern sag. This sag is comparatively rich in oil and gas resources and thus has a relatively good petroleum prospect in the sea.The central sag has also accommodated thick Mesozoic-Cenozoic sediments. The latest research results show that there are three series of hydrocarbon source rocks in the North Yellow Sea Basin, namely, black shales of the Paleogene, Jurassic and Cretaceous. The principal hydrocarbon source rocks in NYSB are the Mesozoic black shale. According to the drilling data of Korea, the black shales of the Paleogene,Jurassic and Cretaceous have all come up to the standards of good and mature source rocks. The NYSB owns an intact system of oil generation, reservoir and capping rocks that can help hydrocarbon to form in the basin and thus it has the great potential of oil and gas. The vertical distribution of the hydrocarbon resources is mainly considered to be in the Cretaceous and then in the Jurassic.


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    Full Text Available The north-east area of Constantine has a very complex geological setting. The variety of sedimentary rocks such as sandstone and clay in abundance, represent a big importance in the industry and road infrastructure. The X-ray diffraction (XRD analysis, Scanning Electron Microscopy SEM/EDS, FTIR spectroscopy of sandstone and clay are required for qualitative and quantitative analysis of the existing phases. In addition, chemical analysis of the same samples is required to confirm the XRD, EDS (Energy Dispersive X ray Spectroscopy and FTIR spectroscopy results. The results of this multidisciplinary study, obtained by various analytical techniques, show a good agreement on the existing phases.

  16. Natural and Laboratory-Induced Compaction Bands in Aztec Sandstone (United States)

    Haimson, B. C.; Lee, H.


    The Aztec sandstone used in this research is from the Valley of Fire State Park area, Nevada. This Jurassic aeolian sandstone is extremely weak (uniaxial compressive strength of 1-2 MPa); porosity averages 26%; grains are subrounded and have a bimodal size distribution (0.1 mm and 0.5 mm); its mineral composition (K. Sternlof, personal comm.) is 93% quartz, 5% k-spar, and 2% kaolinite, Fe carbonate and others; grain bonding is primarily through suturing. Sternlof et al. (EOS, November, 2001) observed substantial exposure of mainly compactive deformation bands in the Aztec sandstone. We studied an SEM image of a compaction band found in a hand sample of the Aztec sandstone. We also conducted a drilling test in a 130x130x180 mm prismatic specimen subjected to a preset far-field true triaxial stress condition (\\sigmah = 15 MPa, \\sigmav = 25 MPa, \\sigmaH = 40 MPa). Drilling of a 20 mm dia. vertical hole created a long fracture-like thin tabular breakout along the \\sigmah springline and perpendicular to \\sigmaH direction. SEM analysis of the zones ahead of the breakout tips revealed narrow bands of presumed debonded intact grains interspersed with grain fragments. We infer that the fragments were formed from multiple splitting or crushing of compacted grains in the band of high compressive stress concentration developed along the \\sigmah springline. SEM images away from the breakout tip surroundings showed no such fragments. SEM study of the natural compaction band showed a similar arrangement of mainly intact grains surrounded by grain fragments. Using the Optimas optical software package, we found the percentage of pore area within the band ahead of the breakout tips to average 17%; outside of this zone it was 23%. In the natural compaction band pore area occupied 8.5% of the band; in the host rock adjacent to the compaction band it averaged 19%. These readings strongly suggest porosity reduction due to compaction in both cases. The close resemblance between the

  17. Cretaceous desert cycles, wind direction and hydrologic cycle variations in Ordos Basin:Evidence for Cretaceous climatic unequability

    Institute of Scientific and Technical Information of China (English)

    JIANG Xinsheng; PAN Zhongxi; XIE Yuan; LI Minghui


    Climatic state under greenhouse effect is a currently hot point. Whether greenhouse climate in geological history, especially in Cretaceous, was equable or not has aroused extensive discussion. By analysis on depositional cyclcity, wind direction change and hydrologic cycle variation of Cretaceous desert in the Ordos Basin of China, the unequability of Cretaceous climate is dealt. It is shown that Cretaceous climate was extremely cyclic, not only having long and mid term but also having strong seasonal even instantaneous changes. Therefore, it is suggested that Cretaceous climate was not equable.

  18. Cretaceous desert cycles, wind direction and hydrologic cycle variations in Ordos Basin: Evidence for Cretaceous climatic unequability

    Institute of Scientific and Technical Information of China (English)

    JIANG; Xinsheng; PAN; Zhongxi; XIE; Yuan; LI; Minghui


    Climatic state under greenhouse effect is a currently hot point. Whether greenhouse climate in geological history, especially in Cretaceous, was equable or not has aroused extensive discussion. By analysis on depositional cyclcity, wind direction change and hydrologic cycle variation of Cretaceous desert in the Ordos Basin of China, the unequability of Cretaceous climate is dealt. It is shown that Cretaceous climate was extremely cyclic, not only having long and mid term but also having strong seasonal even instantaneous changes. Therefore, it is suggested that Cretaceous climate was not equable.

  19. Geology and oil and gas assessment of the Fruitland Total Petroleum System, San Juan Basin, New Mexico and Colorado: Chapter 6 in Geology and Oil and Gas Assessment of the Fruitland Total Petroleum System, San Juan Basin, New Mexico and Colorado (United States)

    Ridgley, J.L.; Condon, S.M.; Hatch, J.R.


    The Fruitland Total Petroleum System (TPS) of the San Juan Basin Province includes all genetically related hydrocarbons generated from coal beds and organic-rich shales in the Cretaceous Fruitland Formation. Coal beds are considered to be the primary source of the hydrocarbons. Potential reservoir rocks in the Fruitland TPS consist of the Upper Cretaceous Pictured Cliffs Sandstone, Fruitland Formation (both sandstone and coal beds), and the Farmington Sandstone Member of the Kirtland Formation, and the Tertiary Ojo Alamo Sandstone, and Animas, Nacimiento, and San Jose Formations.

  20. Crustal rifting and subsidence of Sirte basin, Libya: a mature hydrocarbon Province

    Energy Technology Data Exchange (ETDEWEB)

    Gumati, Y.; Schamel, S.; Nairn, A.E.M.


    The complex rifting and subsidence history of the Sirte basin serves as an instructive case study of the tectonic evolution of an intercratonic extensional basin. The Sirte basin formed by collapse of the Sirte arch in the mid-Cretaceous. Marine sediments accumulated following initial crustal arching and rifting as the basin was flooded from the north. Upper Cretaceous strata lie unconformably on igneous and metamorphic rocks of the Precambrian basement complex, Cambrian-Ordovician Gargaf Group, or the pre-Cretaceous continental Nubian Sandstone. The most rapid subsidence and accumulation of basinal strata occurred in the early Cenozoic; however, the basin has been relatively stable since the Oligocene. The basin is floored by a northwest-southeast-trending mosaic of narrow horsts and grabens, an important structural characteristic that distinguishes it from the adjacent intracratonic Kufra, Murzuk, and Ghadames basins. The details of basin subsidence, sediment accumulation rates, and facies variations have been reconstructed for the northern Sirte basin from a suite of approximately 100 well logs and numerous seismic lines. Subsidence-rate maps for short time intervals from the mid-Cretaceous through the Eocene show a continual shifting of the loci of maximum and minimum subsidence. The nonsteady character of basin subsidence may reflect a periodicity of movement on the major basement-rooted growth faults bounding the underlying horsts and grabens.

  1. Evidence of shallow hydrocarbons offshore northern Santa Cruz county, California

    Energy Technology Data Exchange (ETDEWEB)

    Mullins, H.T.; Nagel, D.K.


    Analyses of high-resolution seismic reflection profiles and hydrocarbon samples indicate that natural hydrocarbon seepage is occurring along the San Gregorio and Monterey Bay fault zones offshore northern Santa Cruz County, California. A variety of anomalous seismic reflection features such as a water-column anomalies, subsurface amplitude anomalies (''bright spots''), and seismic ''smears/wipeouts'' has been observed and mapped. More than 100 water-column anomalies (probably gas seeps) occur in the study area of approximately 270 mi/sup 2/ (700 km/sup 2/). Many of these seismic anomalies are associated with subsurface geologic structures, which suggest hydrocarbon migration from depth. Samples of natural gas collected from a shallow coastal water well contain 74 to 91% methane, 7 to 23% nitrogen, approx.2% carbon dioxide, and < 1% ethane. The methane appears to be thermogenic in origin, having delta/sup 13/C values of -29.51 to -32.55% PDB. Rock dredges from 2,300 ft (700 m) of water in Ascension Submarine Canyon have also recovered oil-saturated sandstones, further suggesting the seepage of hydrocarbons. The shallow occurrence of most of these hydrocarbons are interpreted to be the result of migration from depth along active faults within the San Gregorio and Monterey Bay faults zones.

  2. Provenance of a large Lower Cretaceous turbidite submarine fan complex on the active Laurasian margin: Central Pontides, northern Turkey (United States)

    Akdoğan, Remziye; Okay, Aral I.; Sunal, Gürsel; Tari, Gabor; Meinhold, Guido; Kylander-Clark, Andrew R. C.


    The Pontides formed the southern active margin of Laurasia during the Mesozoic. They became separated from mainland Laurasia during the Late Cretaceous, with the opening of the Black Sea as an oceanic back-arc basin. During the Early Cretaceous, a large submarine turbidite fan complex developed in the Central Pontides. The turbidites cover an area of 400 km by 90 km with a thickness of more than 2 km. We have investigated the provenance of these turbidites-the Çağlayan Formation-using paleocurrent measurements, U-Pb detrital zircon ages, REE abundances of dated zircons and geochemistry of detrital rutile grains. 1924 paleocurrent measurements from 96 outcrop stations indicate flow direction from northwest to southeast in the eastern part of the Çağlayan Basin and from north-northeast to west-southwest in the western part. 1194 detrital zircon ages from 13 Lower Cretaceous sandstone samples show different patterns in the eastern, central and western parts of the basin. The majority of the U-Pb detrital zircon ages in the eastern part of the basin are Archean and Paleoproterozoic (61% of all zircon ages, 337 grains); rocks of these ages are absent in the Pontides and present in the Ukrainian Shield, which indicates a source north of the Black Sea. In the western part of the basin the majority of the zircons are Carboniferous and Neoproterozoic (68%, 246 grains) implying more local sources within the Pontides. The detrital zircons from the central part show an age spectrum as mixture of zircons from western and eastern parts. Significantly, Jurassic and Early Cretaceous zircons make up less than 2% of the total zircon population, which implies lack of a coeval magmatic arc in the region. This is compatible with the absence of the Lower Cretaceous granites in the Pontides. Thus, although the Çağlayan Basin occupied a fore-arc position above the subduction zone, the arc was missing, probably due to flat subduction, and the basin was largely fed from the Ukrainian

  3. Unraveling multiple provenance areas using sandstone petrofacies and geochemistry: An example in the southern flank of the Golfo San Jorge Basin (Patagonia, Argentina) (United States)

    Limarino, Carlos Oscar; Giordano, Sergio Roberto


    The aim of this paper is to study the provenance of Late Cretaceous sandstones deposited along the south flank of the Golfo San Jorge Basin. For this purpose, detrital modes of three hundred thirty-seven sandstone samples collected in the Mina del Carmen, Bajo Barreal, and Cañadón Seco Formations were studied in ten oil fields. According to the modal composition of the sandstones, six petrofacies were defined allowing the identification of not only principal, but also secondary provenance areas. The QVM and VQM petrofacies are more than 20% metamorphic, sedimentary, and polycrystalline quartz clasts (Lm + Ls + Qpg > 20%), evidencing a secondary signal of basement supply masked by a predominant volcanic provenance. The petrofacies VP and VF are characterized by Lm + Ls + Qpg 20%.), which indicate a supply of sediment from volcanic terrains and scarce derivation of materials from basement rocks. Based on the plagioclase/k-feldspar ratio, the VF petrofacies is interpreted to be dominated by the supply of sand grains from the Andean volcanic-arc, while VP is supposed have originated through the erosion of intermediate volcanic rock outcroppings in the Macizo del Deseado. Finally, both the VQ and QV petrofacies show Lm + Ls + Qpg <20% and Pm + Om<20%, indicating a provenance of volcanic areas coupled with minor contributions from basement rocks. During the Late Cretaceous, the Golfo San Jorge Basin underwent a sag phase that was characterized by very scarce volcanism and tectonic activity. Although these conditions did not favor defined patterns in the vertical stacking of petrofacies, the sandstones exhibit remarkable changes in their regional distribution, which were determined by the paleogeography of the basin and differences in basement composition within the source areas. Finally, a paleogeographic model for sediment circulation in the basin is proposed. This model recognizes the main fluvial dispersal trends that flowed northwest to southeast and transported

  4. Trilobites from the Middle Ordovician Stairway Sandstone, Amadeus Basin, central Australia

    DEFF Research Database (Denmark)

    Jakobsen, Kristian Grube; Nielsen, Arne Thorshøj; Harper, David Alexander Taylor;


    During the Middle Ordovician (Darriwilian) sandstones and siltstones were deposited in the epicontinental Larapintine Sea, which covered large parts of central Australia. The Darriwilian Stairway Sandstone has, for the first time, been sampled stratigraphically for macrofossils to track marine be...

  5. Cathodoluminescence investigations on quartz cement in sandstones of Khabour Formation from Iraqi Kurdistan region, northern Iraq

    DEFF Research Database (Denmark)

    Omer, Muhamed Fakhri; Friis, Henrik

    The Ordovician deltaic to shallow marine Khabour Formation in Northern Iraq consists mainly of sandstone with minor siltstone and interbedded shale. The sandstones are pervasively cemented by quartz that resulted in very little preserved primary porosity. Cathodoluminescence and petrographic stud...

  6. Altitude of the bottom of the Trinidad Sandstone in the Raton Basin, Las Animas County, Colorado (United States)

    U.S. Geological Survey, Department of the Interior — This data set consists of structure contours that show lines of equal altitude of the bottom of the Trinidad Sandstone, the contact between the Trinidad Sandstone...

  7. The effect of hot water injection on sandstone permeability

    DEFF Research Database (Denmark)

    Rosenbrand, Esther; Haugwitz, Christian; Jacobsen, Peter Sally Munch;


    Seasonal energy storage can be achieved by hot water injection in geothermal sandstone aquifers. We present an analysis of literature data in combination with new short-term flow through permeability experiments in order to address physical and physico-chemical mechanisms that can alter...


    Institute of Scientific and Technical Information of China (English)

    Wang Zhongmao; Dong Bo; Fu Xiaofeng; Rong Jiashu


    @@ Most of the oil reservoirs in Jilin province occur in fractured sandstone with low permeability and heavy heterogeneity. In addition, with fracture development, the artificial fractures around producing wells and water injection wells have been increased, further aggravating the heterogeneity of oil reservoirs.

  9. Diagenetic effect on permeabilities of geothermal sandstone reservoirs

    DEFF Research Database (Denmark)

    Weibel, Rikke; Olivarius, Mette; Kristensen, Lars

    The Danish subsurface contains abundant sedimentary deposits, which can be utilized for geothermal heating. The Upper Triassic – Lower Jurassic continental-marine sandstones of the Gassum Formation has been utilised as a geothermal reservoir for the Thisted Geothermal Plant since 1984 extracting ...

  10. Diagenesis, provenance and depositional environments of the Bunter Sandstone Formation

    DEFF Research Database (Denmark)

    Olivarius, Mette; Weibel, Rikke; Friis, Henrik

    The Bunter Sandstone Formation in the northern North German Basin has large geothermal potential with high porosity and permeability (generally >15% and >100 mD, respectively) and with pore fluid temperatures that are adequate for geothermal energy production (c. 55–60˚C). A combined investigatio...

  11. Inelastic compaction, dilation and hysteresis of sandstones under hydrostatic conditions (United States)

    Shalev, Eyal; Lyakhovsky, Vladimir; Ougier-Simonin, Audrey; Hamiel, Yariv; Zhu, Wenlu


    Sandstones display non-linear and inelastic behaviour such as hysteresis when subjected to cyclic loading. We present three hydrostatic compaction experiments with multiple loading-unloading cycles on Berea and Darley Dale sandstones and explain their hysteretic behaviour using non-linear inelastic compaction and dilation. Each experiment included eight to nine loading-unloading cycles with increasing maximum pressure in each subsequent cycle. Different pressure-volumetric strain relations during loading and unloading were observed. During the first cycles, under relatively low pressures, not all of the volumetric strain is recovered at the end of each cycle whereas at the last cycles, under relatively high pressures, the strain is recovered and the pressure-volumetric strain hysteresis loops are closed. The observed pressure-volumetric strain relations are non-linear and the effective bulk modulus of the sandstones changes between cycles. Observations are modelled with two inelastic deformation processes: irreversible compaction caused by changes in grain packing and recoverable compaction associated with grain contact adhesion, frictional sliding on grains or frictional sliding on cracks. The irreversible compaction is suggested to reflect rearrangement of grains into a more compact mode as the maximum pressure increases. Our model describes the `inelastic compaction envelope' in which sandstone sample will follow during hydrostatic loading. Irreversible compaction occurs when pressure is greater than a threshold value defined by the `inelastic compaction envelope'.

  12. 古巴地区沉积盆地演化与油气成藏条件%Sedimentary basin evolution and hydrocarbon accumulation conditions in Cuba

    Institute of Scientific and Technical Information of China (English)

    陈榕; 吴朝东; 申延平


    Caribbean Arc over the North America plate promoted the maturation of the source rocks.The large thrust fault zone and faults resulted from arc-continent collision provided the pathways for hydrocarbon migrating to and accumulating in the reservoirs such as the fractured Jurassic-Cretaceous carbonates,fractured volcanic rocks,pyroclastic rock and Paleocene sandstone,leading to the formation of structural,stratigraphic,lithological and composite reservoirs.

  13. Muddy and dolomitic rip-up clasts in Triassic fluvial sandstones: Origin and impact on potential reservoir properties (Argana Basin, Morocco) (United States)

    Henares, Saturnina; Arribas, Jose; Cultrone, Giuseppe; Viseras, Cesar


    The significance of rip-up clasts as sandstone framework grains is frequently neglected in the literature being considered as accessory components in bulk sandstone composition. However, this study highlights the great value of muddy and dolomitic rip-up clast occurrence as: (a) information source about low preservation potential from floodplain deposits and (b) key element controlling host sandstone diagenetic evolution and thus ultimate reservoir quality. High-resolution petrographic analysis on Triassic fluvial sandstones from Argana Basin (T6 and T7/T8 units) highlights the significance of different types of rip-up clasts as intrabasinal framework components of continental sediments from arid climates. On the basis of their composition and ductility, three main types are distinguished: (a) muddy rip-up clasts, (b) dolomitic muddy rip-up clasts and (c) dolomite crystalline rip-up clasts. Spatial distribution of different types is strongly facies-related according to grain size. Origin of rip-up clasts is related to erosion of coeval phreatic dolocretes, in different development stages, and associated muddy floodplain sediments. Cloudy cores with abundant inclusions and clear outer rims of dolomite crystals suggest a first replacive and a subsequent displacive growth, respectively. Dolomite crystals are almost stoichiometric. This composition is very similar to that of early sandstone dolomite cement, supporting phreatic dolocretes as dolomite origin in both situations. Sandstone diagenesis is dominated by mechanical compaction and dolomite cementation. A direct correlation exists between: (1) muddy rip-up clast abundance and early reduction of primary porosity by compaction with irreversible loss of intergranular volume (IGV); and (2) occurrence of dolomitic rip-up clasts and dolomite cement nucleation in host sandstone, occluding adjacent pores but preserving IGV. Both processes affect reservoir quality by generation of vertical and 3D fluid flow baffles and

  14. Lower Cretaceous Dinosaur Tracks from Puebla, Mexico



    Dinosaur tracks have been identified near San Martín Atexcal, southern Puebla, Mexico, within the sedimentary sequence of the San Juan Raya Formation of Lower Cretaceous (Albian) age. The tracksite, located in the bed of the Magdalena River, reveals six different ichnofossiliferous levels identified within a 9 m thick sedimentary sequence. The inferred environment is that of a tidal (marginal marine) mudflat (Level I). Level I preserves three theropods trackways (?Allosauroidea), additionally...

  15. Vertebrate fossils and trace fossils in Upper Jurassic-Lower cretaceous red beds in the Atacama region, Chile (United States)

    Bell, C. M.; Suárez, M.

    Pterosaur, dinosaur, and crocodile bones are recorded here for the first time in Upper Jurassic-Lower Cretaceous red beds in the Atacama region east of Copiapó, Chile. Trace fossils produced by vertebrate animals include the footprints of theropod dinosaurs and the depressions of sandstone laminae interpreted as burrows and foot impressions. The fossils occur in the 1500-meter-thick Quebrada Monardes Formation, which consists predominantly of the aeolian and alluvial deposits of a semi-arid terrestrial environment. Vertebrate fossils are very rare in Chile. Dinosaur bones and footprints have previously been recorded at only seven locations, and pterosaur remains at only one location. The newly discovered dinosaur bones are the oldest to be described in Chile.

  16. New occurrences of microvertebrate fossil accumulations in Bauru Group, Late Cretaceous of western São Paulo state, Brazil (United States)

    Alveş, Y. M.; Bergqvist, L. P.; Brito, P. M.


    In this work, we present the results of several palaeontological expeditions to four Upper Cretaceous fossil microsites of the Adamantina and Presidente Prudente formations in western São Paulo State, Brazil. Despite the fragmentary condition of the fossils recovered, they represent an important record of vertebrate microremains. The material, recovered through screen washing, comprises teeth and scales of Lepisosteidae; two morphotypes of Halecostomi teeth with similarities to Characiformes and Amiiformes; a Teleostei tooth of molariform shape; fin spines of Siluriformes; teeth of possible Baurusuchidae, Notosuchia (probably Adamantinasuchus or Mariliasuchus), Neosuchia (probably Itasuchus or Goniopholis), and other Mesoeucrocodylia indet.; probable teeth of Abelisauroidea, other Theropoda indet., and a phalanx of Aves. The comparative microvertebrate fossil accumulation from western São Paulo State provides evidence that: 1) floodplain channels accumulate large concentrations of microremains; 2) coarse sandstone privileges enamel tissues like teeth and scales; 3) new vertebrate fossil records have been discovered in Florida Paulista, Alfredo Marcondes, and Alvares Machado outcrops.

  17. Early Cretaceous Tectonism and Diatoms in Korea

    Institute of Scientific and Technical Information of China (English)

    Ki-Hong CHANG; Sun-Ok PARK


    The Early Cretaceous Sindong Group, a non-marine molasse, unconformably overlies the folded earliest Cretaceous Myogok Formation. The tectonism that folded the Jaseong Synthem including the Myogok and other formations is here called the Nakdong-Jaeryeonggang (N-J) tectonism. The Oknyeobong and Dabokni Formations are discussed to show that they belong to the Jaseong Synthem. The Dabokni Formation yielded fossil diatoms whose age has been referred as the "earliest Cretaceous" based on the geologically constrained age of the fossil-bearing deposit. The age of the N-J tectonism appears Barremian as it is between the Hauterivian Myogok Formation and the Aptian Sindong Group with the TPN (Trigonioides-Plicatounio-Nippononaia) fauna. The N-J tectonism, an orogeny, quite deformed pre-Aptian strata in Korea, but can hardly find its reported equivalent in NE China. A revised correlation table shows that the Jaseong- Sindong sequence corresponds to the Jehol Group of China. The Sindong-Hayang transition was characterized by basin migration and dextral rotation probably caused by the Tan-Lu fault system in a broad sense.

  18. Measuring and predicting reservoir heterogeneity in complex deposystems: The fluvial-deltaic Big Injun sandstone in West Virginia

    Energy Technology Data Exchange (ETDEWEB)

    Patchen, D.G.; Hohn, M.E.; Aminian, K.; Donaldson, A.; Shumaker, R.; Wilson, T.


    The purpose of this research is to develop techniques to measure and predict heterogeneities in oil reservoirs that are the products of complex deposystems. The unit chosen for study is the Lower Mississippian Big Injun sandstone, a prolific oil producer (nearly 60 fields) in West Virginia. This research effort has been designed and is being implemented as an integrated effort involving stratigraphy, structural geology, petrology, seismic study, petroleum engineering, modeling and geostatistics. Sandstone bodies are being mapped within their regional depositional systems, and then sandstone bodies are being classified in a scheme of relative heterogeneity to determine heterogeneity across depositional systems. Facies changes are being mapped within given reservoirs, and the environments of deposition responsible for each facies are being interpreted to predict the inherent relative heterogeneity of each facies. Structural variations will be correlated both with production, where the availability of production data will permit, and with variations in geologic and engineering parameters that affect production. A reliable seismic model of the Big Injun reservoirs in Granny Creek field is being developed to help interpret physical heterogeneity in that field. Pore types are being described and related to permeability, fluid flow and diagenesis, and petrographic data are being integrated with facies and depositional environments to develop a technique to use diagenesis as a predictive tool in future reservoir development. Another objective in the Big Injun study is to determine the effect of heterogeneity on fluid flow and efficient hydrocarbon recovery in order to improve reservoir management. Graphical methods will be applied to Big Injun production data and new geostatistical methods will be developed to detect regional trends in heterogeneity.

  19. Hydrocarbon potential of hydrocarbon source rocks of the New Siberian Islands, Russian Arctic (United States)

    Gaedicke, Christoph; Sobolev, Peter; Franke, Dieter; Piepjohn, Karsten; Brandes, Christian; Kus, Jolanta; Scheeder, Georg


    The New Siberian Islands are bridging the Laptev Sea with the East Siberian Sea. The Laptev and East Siberian Seas cover large areas of the continental margin of northeastern Arctic Russia. The East Siberian Shelf encompassing an area of 935.000 km2 is still virtually unexplored and most of the geological models for this shelf are extrapolations of the geology of the New Siberian Islands, the Wrangel Island and the northeast Siberian landmass. Apart from few seismic reflection lines, airborne magnetic data were the primary means of deciphering the structural pattern of the East Siberian Shelf. The Laptev Shelf covers an area of about 66.000 km2 and occupies a shelf region, where the active mid-oceanic spreading ridge of the Eurasian Basin hits the slope of the continental margin. During the joint VSEGEI/BGR field expedition CASE 13 (Circum Arctic Structural Events) in summer 2011 we sampled outcrops from the New Siberian Archipelago including the De Long Islands. 102 samples were collected and the Upper Palaeozoic to Lower Cenozoic units are found to be punctuated by several organic-rich intervals. Lithology varies from continental dominated clastic sedimentary rocks with coal seams to shallow marine carbonates and deep marine black shales. Rock-Eval pyrolysis, gas chromatography/mass spectrometry and organic petrography studies were performed to estimate organic matter contents, composition, source, and thermal maturity. According to the results of our analyses, samples from several intervals may be regarded as potential petroleum source rocks. The Lower Devonian shales have the highest source rock potential of all Paleozoic units. Triassic samples have a good natural gas potential. Cretaceous and Cenozoic low-rank coals, lignites, and coal-bearing sandstones display some gas potential. The kerogen of type III (humic, gas-prone) dominates. Most of the samples (except some of Cretaceous and Paleogene age) reached the oil generation window.

  20. Late Cretaceous - Eocene evolution of the Kronotsk arc (United States)

    Shapiro, M. N.; Khotin, M. Y.


    Eastern peninsulas of Kamchatka and probably Komandorskiy Islands form Kronotsk paleoarc. Main components uniting these blocks in a single structure are Paleocene-Eocene subduction-related volcanics. The lowest part of this formation on the Kronotsk peninsula was dated as the Late Senonian. Paleomagnetic data show that, 60-40 Myr ago, Kronotsk arc undergo large northern drift after a nearly equal period of southern drift. The southern part of the Kamchatskiy Mys peninsula, Africa block, is interpreted as a fragment of the accretionary prism of the Kronotsk arc, related to period of the southern drift. There are five main parts of this prism: Olenegorsk gabbro (50-70 Ma); Smaginsk Fm (Albian-Senomanian, 110-95 Ma): hot-spot basaltes and pelagic sediments; Pickezh Fm (Campanian - Maastrichtian, 85-65 Ma): tuffites in the lower part and subarcosic sandstones in the upper; and Soldatsk ultramafics. These parts of the prism are mostly separated by the large thrusts, but locally we saw the konglobrechia with gabbroic and diabasic clasts in the lowest parts of the Smaginsk and Pickezh sequences. The transition from the Pickezh Fm to Pickezh sanstones was always described as gradual. Six published paleomagnetic determinations (from Campanian to Bartonian, 80-40 Ma) of Kronotsk arc volcanics, kinematics of the large plates in the Northern Pacific, and some geological data allow us to reconstruct the drift of the Kronotsk arc at the end of Cretaceous and the first half of Paleogene. 80-60 Myr ago, Kronotsk arc marked a southern margin of the North American Plate (or a little plate with the very similar kinematics) when the Kula plate was consumed in the Kronotsk while the Kula-Pacific Ridge and Hawaiian hot spot were placed to the south. The apron of tuffs and tuffites overlapped the slopes of the newly arc and neighboring oceanic structures. One of the latter, Smaginsk oceanic plateau on the Kula plate was partly separated from this plate and attached to the Kronotsk

  1. Geological and petrophysical characterization of the Ferron Sandstone for 3-D simulation of a fluvial-deltaic reservoir. Technical progress report, January 1, 1995--March 31, 1995

    Energy Technology Data Exchange (ETDEWEB)

    Allison, M.L.


    The objective of this project is to develop a comprehensive, interdisciplinary, and quantitative characterization of a fluvial-deltaic reservoir which will allow realistic inter-well and reservoir-scale modeling to be developed for improved oil-field development in similar reservoirs world-wide. The geological and petrophysical properties of the Cretaceous Ferron Sandstone in east-central Utah will be quantitatively determined. Both new and existing data will be integrated into a three-dimensional representation of spatial variations in porosity, storativity, and tensorial rock permeability at a scale appropriate for inter-well to regional-scale reservoir simulation. Results could improve reservoir management through proper infill and extension drilling strategies, reduction of economic risks, increased recovery from existing oil fields, and more reliable reserve calculations. Transfer of the project results to the petroleum industry is an integral component of the project.

  2. Multidisciplinary studies on ancient sandstone quarries of Western Sardinia (Italy). (United States)

    Grillo, Silvana Maria; Del Vais, Carla; Naitza, Stefano


    The ancient coastal quarries of Mediterranean are increasingly considered geosites of multidisciplinary relevance. They are sites of historical-archaeological interest that show ancient techniques of stone extraction; they are significant for cultural heritage conservation and restoration, as sources of the stones used in ancient buildings and monuments; they are sites of geological relevance, as often retain important stratigraphic sections; they are also useful markers of secular changes in the sea level. A multisciplinary study is in progress on the ancient quarries of the Sinis region (western Sardinia island), integrating archaeological, geological, minero-petrographical data. In Sardinia, coastal quarries have been established from Punic and Roman times. Many of them exploited Quaternary sediments along the southern and western coasts of the island. They consist of middle-late Pleistocene marine conglomerates and carbonate sandstones, and of coastal (aeolian) carbonate sandstones. Sandstone blocks of different sizes have been widely used in ancient cities for buildings, defensive works, harbours, etc. Three main areas of stone extraction (San Giovanni di Sinis, Punta Maimoni, Is Arutas) have been so far recognized in the Sinis. GIS-supported mapping and documentation of the sites includes their geology and stratigraphy, the extension and layout of the quarries, and an evaluation of volumes of extracted rocks. Documented archaeological evidences include ancient extraction fronts, spoil heaps, working areas, working traces in the old fronts, transport routes of blocks, and traces of loading facilities. The study is aimed at reconstructing the relationships of the quarries with the urban areas of Sinis, as the ancient Punic-Roman city of Tharros. Consequently, a minero-petrographical characterization (optical microscopy, XRD) is performed on sandstones sampled in each quarry, and in historical buildings in Tharros and other centres of the region (Cabras

  3. Cretaceous sedimentation in the outer Eastern Carpathians: Implications for the facies model reconstruction of the Moldavide Basin (United States)

    Roban, R. D.; Krézsek, C.; Melinte-Dobrinescu, M. C.


    The mid Cretaceous is characterized by high eustatic sea-levels with widespread oxic conditions that made possible the occurrence of globally correlated Oceanic Red Beds. However, very often, these eustatic signals have been overprinted by local tectonics, which in turn resulted in Lower Cretaceous closed and anoxic basins, as in the Eastern Carpathians. There, the black shale to red bed transition occurs in the latest Albian up to the early Cenomanian. Although earlier studies discussed the large-scale basin configuration, no detailed petrography and sedimentology study has been performed in the Eastern Carpathians. This paper describes the Hauterivian to Turonian lithofacies and interprets the depositional settings based on their sedimentological features. The studied sections crop out only in tectonic half windows of the Eastern Carpathians, part of the Vrancea Nappe. The lithofacies comprises black shales interbedded with siderites and sandstones, calcarenites, marls, radiolarites and red shales. The siliciclastic muddy lithofacies in general reflects accumulation by suspension settling of pelagites and hemipelagites in anoxic (black shale) to dysoxic (dark gray and gray to green shales) and oxic (red shales) conditions. The radiolarites alternate with siliceous shales and are considered as evidence of climate changes. The sandstones represent mostly low and high-density turbidite currents in deep-marine lobes, as well as channel/levee systems. The source area is an eastern one, e.g., the Eastern Carpathians Foreland, given the abundance of low grade metamorphic clasts. The Hauterivian - lower Albian sediments are interpreted as deep-marine, linear and multiple sourced mud dominated systems deposited in a mainly anoxic to dysoxic basin. The anoxic conditions existed in the early to late Albian, but sedimentation changed to a higher energy mud/sand-dominated submarine channels and levees. This coarsening upwards tendency is interpreted as the effect of the

  4. Geochemical fingerprints and pebbles zircon geochronology: Implications for the provenance and tectonic setting of Lower Cretaceous sediments in the Zhucheng Basin (Jiaodong peninsula, North China)

    Indian Academy of Sciences (India)

    Jin-Long Ni; Jun-Lai Liu; Xiao-Ling Tang; Xiao-Xiao Shi; Hong Zhang; Shuai Han


    This paper conducts a petrogeochemical analysis of the Lower Cretaceous Laiyang Group’s sandstones, compares the results with the Neoproterozoic and Mesozoic intrusive rocks in the southern Sulu Orogen (also called the Jiaonan Orogen), and performs an LA-ICP-MS zircon geochronology analysis of the granitic gneisses in the conglomerates of the Laiyang Group and the intrusive rocks in the JiaonanOrogen. The results show that the major element proportions of the Longwangzhuang Formation (LWZ Fm) and Qugezhuang Formation (QGZ Fm) of the Laiyang Group in the Zhucheng Basin are similar. The values of various indices for the LWZ Fm are similar to the average sandstone content of activecontinental margins, whereas, the values for the QGZ Fm are similar to those of continental island arcs. The comparison shows that the REE characteristics of the LWZ Fm and QGZ Fm of Laiyang Group are similar to those of the Neoproterozoic granitic gneisses in the Jiaonan Orogen but obviously different from those of the Early Cretaceous intrusive rocks. A tectonic setting discrimination diagram revealsthat the provenance of the Laiyang Group includes features of active continental margins and continental island arcs. A number of indicators, e.g., the sandstone type, the Chemical Index of Alteration, the Chemical Index of Weathering, the Plagioclase Index of Alteration and the Index of Chemical Constituent Variation, indicated that the sandstones did not undergo intense weathering and were deposited near the source area. The zircon ages of the granitic gneiss material in the conglomerates at the base of the Laiyang Group are 790±8.4 Ma, close to the ages of the Neoproterozoic granitic gneiss in the Jiaonan Orogen (739–819 Ma), and very different from the ages of the Early Cretaceous intrusive rocks. Combiningwith paleocurrent directions, geochemical character, the Neoproterozoic granitic gneisses in the Jiaonan Orogen may represent the primary provenance of the Laiyang Group in the

  5. Geochemical fingerprints and pebbles zircon geochronology: Implications for the provenance and tectonic setting of Lower Cretaceous sediments in the Zhucheng Basin (Jiaodong peninsula, North China) (United States)

    Ni, Jin-Long; Liu, Jun-Lai; Tang, Xiao-Ling; Shi, Xiao-Xiao; Zhang, Hong; Han, Shuai


    This paper conducts a petrogeochemical analysis of the Lower Cretaceous Laiyang Group's sandstones, compares the results with the Neoproterozoic and Mesozoic intrusive rocks in the southern Sulu Orogen (also called the Jiaonan Orogen), and performs an LA-ICP-MS zircon geochronology analysis of the granitic gneisses in the conglomerates of the Laiyang Group and the intrusive rocks in the Jiaonan Orogen. The results show that the major element proportions of the Longwangzhuang Formation (LWZ Fm) and Qugezhuang Formation (QGZ Fm) of the Laiyang Group in the Zhucheng Basin are similar. The values of various indices for the LWZ Fm are similar to the average sandstone content of active continental margins, whereas, the values for the QGZ Fm are similar to those of continental island arcs. The comparison shows that the REE characteristics of the LWZ Fm and QGZ Fm of Laiyang Group are similar to those of the Neoproterozoic granitic gneisses in the Jiaonan Orogen but obviously different from those of the Early Cretaceous intrusive rocks. A tectonic setting discrimination diagram reveals that the provenance of the Laiyang Group includes features of active continental margins and continental island arcs. A number of indicators, e.g., the sandstone type, the Chemical Index of Alteration, the Chemical Index of Weathering, the Plagioclase Index of Alteration and the Index of Chemical Constituent Variation, indicated that the sandstones did not undergo intense weathering and were deposited near the source area. The zircon ages of the granitic gneiss material in the conglomerates at the base of the Laiyang Group are 790 ± 8.4 Ma, close to the ages of the Neoproterozoic granitic gneiss in the Jiaonan Orogen (739-819 Ma), and very different from the ages of the Early Cretaceous intrusive rocks. Combining with paleocurrent directions, geochemical character, the Neoproterozoic granitic gneisses in the Jiaonan Orogen may represent the primary provenance of the Laiyang Group in the

  6. Diagenetic fluids evolution and genetic mechanism of tight sandstone gas reservoirs in Upper Triassic Xujiahe Formation in Sichuan Basin, China

    Institute of Scientific and Technical Information of China (English)


    The reservoirs of the Upper Triassic Xujiahe Formation in Sichuan Basin have the characteristics of low compositional maturity, low contents of cements and medium textural maturity. The general physical properties of the reservoirs are poor, with low porosity and low permeability, and there are only a few reservoirs with medium porosity and low permeability in local areas. Based on the diagenetic mineral association, a diagenetic sequence of cements is established: early calcites (or micrite siderites) →first quartz overgrowth→chlorite coatings→dissolution of feldspars and debris→chlorite linings→ second quartz overgrowth (quartz widen or filled in remain intergranular pores and solution pores)→dissolution→third quartz overgrowth (quartz filled in intergranular and intragranular solution pores)→intergrowth (ferro) calcites→dolomites→ferro (calcites) dolomites→later dissolution→veins of quartz and calcites formation. Mechanical compaction is the main factor in making the reservoirs tight in the basin, followed by the second and third quartz overgrowth. In a long-term closed system, only feld-spars and some lithic fragments are dissolved by diagenetic fluids, while intergranular cements such as quartz and calcit are not dissolved and thus have little influence on the porosity of the Xujiahe Formation. This is the third factor that may have kept the sandstones of Xujiahe Formation tight finally. The hydrocarbon was extensively generated from organic materials after the second quartz overgrowth, and selectively entered favorable reservoirs to form tight sandstone gas reservoirs.

  7. Diagenetic fluids evolution and genetic mechanism of tight sandstone gas reservoirs in Upper Triassic Xujiahe Formation in Sichuan Basin, China

    Institute of Scientific and Technical Information of China (English)

    ZHU RuKai; ZOU CaiNeng; ZHANG Nai; WANG XueSong; CHENG Rong; LIU LiuHong; ZHOU ChuanMin; SONG LiHong


    The reservoirs of the Upper Triassic Xujiahe Formation in Sichuan Basin have the characteristics of low compositional maturity, low contents of cements and medium textural maturity.The general physical properties of the reservoirs are poor, with low porosity and low permeability, and there are only a few reservoirs with medium porosity and low permeability in local areas.Based on the diagenetic mineral association, a diagenetic sequence of cements is established: early calcites (or micrite siderites)→ first quartz overgrowth→chlorite coatings→dissolution of feldspars and debris→chlorite linings→ second quartz overgrowth (quartz widen or filled in remain intergranular pores and solution pores→ dissolution→third quartz overgrowth (quartz filled in intergranular and intragranular solution pores)→ intergrowth (ferro) calcites→dolomites→ferro (calcites) dolomites→later dissolution→veins of quartz and calcites formation.Mechanical compaction is the main factor in making the reservoirs tight in the basin, followed by the second and third quartz overgrowth.In a long-term closed system, only feldspars and some lithic fragments are dissolved by diagenetic fluids, while intergranular cements such as quartz and calcit are not dissolved and thus have little influence on the porosity of the Xujiahe Formation.This is the third factor that may have kept the sandstones of Xujiahe Formation tight finally.The hydrocarbon was extensively generated from organic materials after the second quartz overgrowth, and selectively entered favorable reservoirs to form tight sandstone gas reservoirs.

  8. Distribution and nature of fault architecture in a layered sandstone and shale sequence: An example from the Moab fault, Utah (United States)

    Davatzes, N.C.; Aydin, A.


    We examined the distribution of fault rock and damage zone structures in sandstone and shale along the Moab fault, a basin-scale normal fault with nearly 1 km (0.62 mi) of throw, in southeast Utah. We find that fault rock and damage zone structures vary along strike and dip. Variations are related to changes in fault geometry, faulted slip, lithology, and the mechanism of faulting. In sandstone, we differentiated two structural assemblages: (1) deformation bands, zones of deformation bands, and polished slip surfaces and (2) joints, sheared joints, and breccia. These structural assemblages result from the deformation band-based mechanism and the joint-based mechanism, respectively. Along the Moab fault, where both types of structures are present, joint-based deformation is always younger. Where shale is juxtaposed against the fault, a third faulting mechanism, smearing of shale by ductile deformation and associated shale fault rocks, occurs. Based on the knowledge of these three mechanisms, we projected the distribution of their structural products in three dimensions along idealized fault surfaces and evaluated the potential effect on fluid and hydrocarbon flow. We contend that these mechanisms could be used to facilitate predictions of fault and damage zone structures and their permeability from limited data sets. Copyright ?? 2005 by The American Association of Petroleum Geologists.

  9. Spatial Persistence of Macropores and Authigenic Clays in a Reservoir Sandstone: Implications for Enhanced Oil Recovery and CO2 Storage (United States)

    Dewers, T. A.


    Multiphase flow in clay-rich sandstone reservoirs is important to enhanced oil recovery (EOR) and the geologic storage of CO2. Understanding geologic controls on pore structure allows for better identification of lithofacies that can contain, storage, and/or transmit hydrocarbons and CO2, and may result in better designs for EOR-CO2 storage. We examine three-dimensional pore structure and connectivity of sandstone samples from the Farnsworth Unit, Texas, the site of a combined EOR-CO2 storage project by the Southwest Regional Partnership on Carbon Sequestration (SWP). We employ a unique set of methods, including: robotic serial polishing and reflected-light imaging for digital pore-structure reconstruction; electron microscopy; laser scanning confocal microscopy; mercury intrusion-extrusion porosimetry; and relative permeability and capillary pressure measurements using CO2 and synthetic formation fluid. Our results link pore size distributions, topology of porosity and clay-rich phases, and spatial persistence of connected flow paths to multiphase flow behavior. The authors gratefully acknowledge the U.S. Department of Energy's National Energy Technology Laboratory for sponsoring this project through the SWP under Award No. DE-FC26-05NT42591. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

  10. Cretaceous gastropods: contrasts between tethys and the temperate provinces. (United States)

    Sohl, N.F.


    During the Cretaceous Period, gastropod faunas show considerable differences in their evolution between the Tethyan Realm (tropical) and the Temperate Realms to the north and south. Like Holocene faunas, prosobranch, gastropods constitute the dominant part of Cretaceous marine snail faunas. Entomotaeneata and opisthobranchs usually form all of the remainder. In Tethyan faunas the Archaeogastropoda form a consistent high proportion of total taxa but less than the Mesogastropoda throughout the period. In contrast, the Temperate faunas beginning in Albian times show a decline in percentages of archaeogastropod taxa and a significant increase in the Neogastropoda, until they constitute over 50 percent of the taxa in some faunas. The neogastropods never attain high diversity in the Cretaceous of the Tethyan Realm and are judged to be of Temperate Realm origin. Cretaceous Tethyan gastropod faunas are closely allied to those of the 'corallien facies' of the Jurassic and begin the period evolutionarily mature and well diversified. Three categories of Tethyan gastropods are analyzed. The first group consists of those of Jurassic ancestry. The second group orginates mainly during the Barremian and Aptian, reaches a climax in diversification during middle Cretaceous time, and usually declines during the latest Cretaceous. The third group originates late in the Cretaceous and consists of taxa that manage to either survive the Cretaceous-Tertiary crisis or give rise to forms of prominence among Tertiary warm water faunas. Temperate Realm gastropod faunas are less diverse than those of Tethys during the Early Cretaceous. They show a steady increase in diversity, primarily among the Mesogastropoda and Neogastropoda. This trend culminates in latest Cretaceous times when the gastropod assemblages of the clastic provinces of the inner shelf contain an abundance of taxa outstripping that of any other part of the Cretaceous of either realm. Extinction at the Cretaceous

  11. Dating hydrocarbon genera-tion and migration based on bitumen reflectance

    Institute of Scientific and Technical Information of China (English)


    On the basis of thermal maturation theories of organic matter in sediments and an improved Karweil's method, a method for dating hydrocarbon generation and migration by means of bitumen reflectance has been suggested. A few representative boreholes in the Tazhong Area of the Tarim Basin was investigated by this method. The results indicate that the three phases of bitumen from the Tazhong Area formed during Middle and Late Ordovician, Late Cretaceous-Early Tertiary, and Late Tertiary, respectively. This implicates that there were three phases of hydrocarbon generation and migration occurring in this area during geological history. This study provided a new idea for the geological application of geochemical data of bitumen.

  12. Hydrocarbon occurrence in NW Africa's MSGBC area

    Energy Technology Data Exchange (ETDEWEB)

    Reymond, A.; Negroni, P.


    The MSGBC (Mauritania, Senegal, The Gambia, Guinea-Bissau, Guinea Conakry) coastal basin has evolved as a passive margin from Jurassic time up to the present following a period of poorly known rifting of Permian to Middle Jurassic age. Structural configuration of the Paleozoic series is documented by large outcrops and a good number of seismic sections. Based on previous exploration efforts that found significant hydrocarbon shows, a comprehensive study of this African basin's source rocks, maturation evolution and petroleum generation potential was undertaken. About 1,000 geochemical analyses of the Paleozoic, Cretaceous and Tertiary series identified good source rocks in the Cenomano-Turonian, Silurian, Senonian and Paleocene ages. The parameters used to identify and characterize source rock are: Total organic carbon content (TOC) in percent and source potential (in kg HC/t), representing the amount of hydrocarbon generated per ton of rock and determined by Rock-Eval pyrolysis.

  13. Traces of the heritage arising from the Macelj sandstone (United States)

    Golež, Mateja


    The landscape of Southeast Slovenia and its stone heritage principally reveal itself through various Miocene sandstones. The most frequently found type on the borderline between Slovenia and Croatia, i.e. east of Rogatec, is the micaceous-quartz Macelj sandstone. This rock ranges in colour from greenish grey to bluish grey and yellowish, depending on the content of glauconite, which colours it green. In its composition, the rock is a heterogeneous mixture of grains of quartz, dolomite, muscovite, microcline, anorthite and glauconite. The average size of grains is 300μm. In cross-section, they are oblong, semi-rounded or round. The mechanical-physical and durability properties of the Macelj sandstone, which have been characterised pursuant to the applicable standards for natural stone, reveal that the rock exhibits poor resistance to active substances from the atmosphere, particularly in the presence of salt. In the surroundings of Rogatec, there are around 45 abandoned quarries of the Macelj sandstone, which are the result of the exploitation of this mineral resource from the 17th century on. The local quarrymen earned their bread until 1957, when the Kambrus quarry industry closed down. From the original use of this mineral resource as construction and decorative material, the useful value of the Macelj sandstone expanded during the development of the metals industry to the manufacture of large and small grindstones for the needs of the domestic and international market. Therefore, traces of quarrying can not only be seen in the disused quarries, but also in the rich architectural heritage of Rogatec and its surroundings, the stone furniture - from portals, window frames, wells, various troughs, pavements to stone walls - and other. The living quarrying heritage slowly passed into oblivion after World War II, although the analysis of the social image of the people residing in Rogatec and its surroundings revealed that there was an average of one stonemason in

  14. Origins of massive-type sandstones in braided river systems (United States)

    Martin, Charlotte A. L.; Turner, Brian R.


    This study details largely ignored massive-type, predominantly structureless sandstones preserved within braided fluvial successions of Carboniferous to Triassic age. Architectural element analysis reveals that these sediments were deposited within sand-dominated perennial systems of low braiding index. Cross-stratified braid bar deposits are interbedded with, and laterally equivalent to geometrically distinct, largely structureless massive-type sandbodies identified as two separate architectural elements: channel-like (SMC) and sheet-like (SMS). Sub-divisions within these broad categories define six geometric units which are texturally distinct from each other and from the structured sediments of the same lithological unit. Since massive-type sandstone elements have many features in common with the deposits of highly concentrated, laminar sediment/water flows, they are interpreted in terms of similar depositional processes. SMC elements form elongate channel-like features which trend both at high angles to, and parallel with, the palaeoflow of host fluvial channels. The lower bounding surfaces of SMC elements may be either erosive or non-erosive, and describe symmetrical cross-sections with margins dipping debris flows related to fluvial bank and/or bar collapse. SMS elements form sandsheets up to 8 m in thickness which may be traced >250 m parallel and transverse to the fluvial palaeoflow direction established from cross-stratified sandstones of adjacent architectural elements. The basal surface of SMS elements may either be undulose (where the sandbodies are termed SMSU) or erosional (where they are termed SMSE). Internally SMSU elements preserve parallel laminae marginal to basal scours, diffuse sweeping laminae, isolated cross-sets and water escape structures. The SMSU sediments are compositionally identical to the structured sandstones with which they are associated and are interpreted as the result of deposition from highly concentrated stream flows

  15. Libyan Paleozoic: A review of the factors limiting hydrocarbon potential

    Energy Technology Data Exchange (ETDEWEB)

    Kanes, W.H.; Mairn, A.E.M.; Aburawi, R.M.


    Of the three main Paleozoic basins - Ghadames, Murquz, and Kufra - only the Ghadames and its continuation into Algeria, the Illizi (or Fort Polignac) basin, has yielded hydrocarbons in significant quantity. The Paleozoic on the Cyrenaica platform and basement of the Sirte basin has a potential not fully considered. The paleogeography of the Paleozoic system is reviewed to illustrate the extent to which inherited and reactivated basement-controlled structures have influenced later Paleozoic sedimentation and hence the distribution of source rocks, reservoirs, and seals. In all instances, the source rocks are restricted to shales of the Tanezufft Formation or occur in the Upper Devonian Aouinet Oeunine Formation. Multiple fine-grained sequences serve as seals in all the fields. The reservoirs range from the well-cemented but highly fractured Cambrian-Ordovician Gargaf sandstones to the Acacus-Tadrart clastics to the fine-grained Lower Carboniferous Tahara Sandstone. The principal plays are associated with minor structures, and stratigraphic trapping mechanisms play a minor role. The average field size (excluding the Sirte basin) is approximately 80 million bbl of recoverable oil. Paleozoic structural plays in the Sirte basin and the Cyrenaica platform include reactivated infra-Cambrian faults. The lower Paleozoic accumulations of the Murzuq basin are tied to large structures. With the exception of local areas in the Ghadames basin, the Paleozoic succession remains a stratigraphic frontier province - still incompletely explored but with several interesting possibilities for large amounts of stratigraphically trapped hydrocarbons.

  16. The Tendaguru Formation (Late Jurassic to Early Cretaceous, southern Tanzania: definition, palaeoenvironments, and sequence stratigraphy

    Directory of Open Access Journals (Sweden)

    R. Bussert


    Full Text Available The well-known Late Jurassic to Early Cretaceous Tendaguru Beds of southern Tanzania have yielded fossil plant remains, invertebrates and vertebrates, notably dinosaurs, of exceptional scientific importance. Based on data of the German-Tanzanian Tendaguru Expedition 2000 and previous studies, and in accordance with the international stratigraphic guide, we raise the Tendaguru Beds to formational rank and recognise six members (from bottom to top: Lower Dinosaur Member, Nerinella Member, Middle Dinosaur Member, Indotrigonia africana Member, Upper Dinosaur Member, and Rutitrigonia bornhardti-schwarzi Member. We characterise and discuss each member in detail in terms of derivation of name, definition of a type section, distribution, thickness, lithofacies, boundaries, palaeontology, and age. The age of the whole formation apparently ranges at least from the middle Oxfordian to the Valanginian through Hauterivian or possibly Aptian. The Tendaguru Formation constitutes a cyclic sedimentary succession, consisting of three marginal marine, sandstone-dominated depositional units and three predominantly coastal to tidal plain, fine-grained depositional units with dinosaur remains. It represents four third-order sequences, which are composed of transgressive and highstand systems tracts. Sequence boundaries are represented by transgressive ravinement surfaces and maximum flooding surfaces. In a more simple way, the depositional sequences can be subdivided into transgressive and regressive sequences/systems tracts. Whereas the transgressive systems tracts are mainly represented by shallow marine shoreface, tidal channel and sand bar sandstones, the regressive systems tracts predominantly consist of shallow tidal channel, tidal flat, and marginal lagoonal to supratidal deposits. doi:10.1002/mmng.200900004

  17. A refined genetic model for the Laisvall and Vassbo Mississippi Valley-type sandstone-hosted deposits, Sweden: constraints from paragenetic studies, organic geochemistry, and S, C, N, and Sr isotope data (United States)

    Saintilan, Nicolas J.; Spangenberg, Jorge E.; Samankassou, Elias; Kouzmanov, Kalin; Chiaradia, Massimo; Stephens, Michael B.; Fontboté, Lluís


    hydrocarbons in sandstone. Other minor H2S sources are identified. Upward migration and fluctuation of the hydrocarbon-water interface in sandstone below shale aquicludes and the formation of H2S along this interface explain the shape of the orebodies that splay out like smoke from a chimney and the conspicuous alternating layers of galena and sphalerite. Intimate intergrowth of bitumen with sphalerite suggests that subordinate amounts of H2S might have been produced by TSR during Pb-Zn mineralization. Gas chromatograms of the saturated hydrocarbon fraction from organic-rich shale and from both mineralized and barren sandstone samples indicate that hydrocarbons migrated from source rocks in the overlying Alum Shale Formation buried in the foredeep into sandstone, where they accumulated in favorable traps in the forebulge setting.

  18. Oxygenated Derivatives of Hydrocarbons (United States)

    For the book entitled “Insect Hydrocarbons: Biology, Biochemistry and Chemical Ecology”, this chapter presents a comprehensive review of the occurrence, structure and function of oxygenated derivatives of hydrocarbons. The book chapter focuses on the occurrence, structural identification and functi...

  19. Hydrocarbon Spectral Database (United States)

    SRD 115 Hydrocarbon Spectral Database (Web, free access)   All of the rotational spectral lines observed and reported in the open literature for 91 hydrocarbon molecules have been tabulated. The isotopic molecular species, assigned quantum numbers, observed frequency, estimated measurement uncertainty and reference are given for each transition reported.

  20. New dinosaur fossils from ANA locality, Arcillas de Morella Formation (Aptian, Lower Cretaceous, Cinctorres, Spain) (United States)

    Santos-Cubedo, A.; de Santisteban, C.; Suñer, M.; Galobart, A.


    Ana is one of the several dinosaur bone sites located in the Arcillas de Morella Formation (Aptian, Lower Cretaceous; eastern Iberian Chain, Spain). This site was discovered in 1998, but it remained unexcavated until 2002, when a palaeontologist team formed by members of the Institut Paleontología Miquel Crusafont from Sabadell and the Grup Guix from Vila-real unearthed the first fossil from the locality. Nowadays there are five hundred fossils collected, including vertebrate and invertebrate species. Dinosaur bones (Theropoda and Ornithopoda) are abundant in this assemblage and in the last field season bones determined as Sauropoda were found. Taxonomically, Ana is dominated by disarticulated remains of Ornithopoda, which are usually fragmentary and abraded. Many of the elements may have been reworked (spatial averaging and/or time averaging), and the fossil concentration constitutes an autochthonous to parautochthonous association, in a spatial sense. The remains found in the Ana fossils site are placed in sandstones and limes containing marine autochthonous fauna. These deposits were formed during the transgressive infilling of an incised valley. Sedimentological features indicate that fossils were finally deposited in starved shallow estuarine environment. Mineralogically, the sediment including the fossils contains grains of quartz, illite/mica, kaolinite/clorite, K-feldspar and plagioclase, distributed in two mainly grain populations, a silty-clay and a coarse sand size grain, indicating that the sediments were bedded in a low-medium energy depositional environment. Nowadays we identified in Ana, teeth of Theropoda indet. and Baryonychinae indet., and bones of Iguanodon sp. Herein, we report new fossil findings from Ana site. These materials have been determined as Iguanodontia, Titanosauriformes and Theropoda. These new findings will help to understand the dinosaur fauna present in the Lower Cretaceous of Els Ports (Castellón, Spain). Acknowledgments This

  1. Cretaceous (Late Albian) coniferales of Alexander Island, Antarctica. 1: Wood taxonomy: a quantitative approach. (United States)

    Falcon-Lang; Cantrill


    Silicified conifer woods are very common in the mid-Cretaceous (Late Albian, 100Ma) Triton Point Member of the Neptune Glacier Formation (Fossil Bluff Group), SE Alexander Island, Antarctica. These occur as up to 7m high in situ tree trunks and stumps rooted in carbonaceous palaeosols and as allochthonous logs and wood fragments in fluvial channel and sheet sandstone facies. Sixty-eight wood samples were examined in this study and were classified in terms of five form taxa using a quantitative approach. Araucarioxylon (1.5% of specimens) is characterised by dominantly multiseriate, alternately arranged bordered pitting on radial tracheid walls and by 1-4 araucarioid cross-field pitting. Araucariopitys (11.8% of specimens) is characterised by dominantly uniseriate tracheid pitting with subordinate biseriate, alternate tracheid pitting and by 1-4 araucarioid cross-field pitting. Podocarpoxylon sp. 1 (63.1% of specimens) is characterised by contiguous, uniseriate tracheid pitting and 1-2 podocarpoid cross-field pits. Podocarpoxylon sp. 2 (22.1% of specimens) is similar to P. sp. 1, differing only in that ray height is lower, tracheid pits are dominantly spaced more than one pit diameter apart and abundant axial parenchyma is present. These first four taxa all possess growth rings with subtle boundaries. Taxodioxylon (1.5% of specimens) is characterised by 1-2 seriate, oppositely arranged, bordered tracheid pitting, 1-2 taxodioid cross-field pitting and very marked ring boundaries. These woods were derived from large trees with basal stump diameters of up to 0.5m and probable heights of up to 29m. Data from leaf traces suggest that Araucariopitys and Podocarpoxylon sp. 1 and sp. 2 (97% of specimens) were evergreen with leaf retention times of >5years. These predominantly evergreen conifer forests grew in a mild, high latitude (75 degrees S) environment during the mid-Cretaceous greenhouse climate phase.

  2. Fracture propagation in sandstone and slate e Laboratory experiments, acoustic emissions and fracture mechanics

    Institute of Scientific and Technical Information of China (English)

    Ferdinand Stoeckhert; Michael Molenda; Sebastian Brenne; Michael Alber


    abstract Fracturing of highly anisotropic rocks is a problem often encountered in the stimulation of unconven-tional hydrocarbon or geothermal reservoirs by hydraulic fracturing. Fracture propagation in isotropic material is well understood but strictly isotropic rocks are rarely found in nature. This study aims at the examination of fracture initiation and propagation processes in a highly anisotropic rock, specifically slate. We performed a series of tensile fracturing laboratory experiments under uniaxial as well as triaxial loading. Cubic specimens with edge lengths of 150 mm and a central borehole with a diameter of 13 mm were prepared from Fredeburg slate. An experiment using the rather isotropic Bebertal sandstone as a rather isotropic rock was also performed for comparison. Tensile fractures were generated using the sleeve fracturing technique, in which a polymer tube placed inside the borehole is pressurized to generate tensile fractures emanating from the borehole. In the uniaxial test series, the loading was varied in order to observe the transition from strength-dominated fracture propagation at low loading mag-nitudes to stress-dominated fracture propagation at high loading magnitudes.

  3. Plasma devices for hydrocarbon reformation

    KAUST Repository

    Cha, Min Suk


    Plasma devices for hydrocarbon reformation are provided. Methods of using the devices for hydrocarbon reformation are also provided. The devices can include a liquid container to receive a hydrocarbon source, and a plasma torch configured to be submerged in the liquid. The plasma plume from the plasma torch can cause reformation of the hydrocarbon. The device can use a variety of plasma torches that can be arranged in a variety of positions in the liquid container. The devices can be used for the reformation of gaseous hydrocarbons and/or liquid hydrocarbons. The reformation can produce methane, lower hydrocarbons, higher hydrocarbons, hydrogen gas, water, carbon dioxide, carbon monoxide, or a combination thereof.

  4. Plant hydrocarbon recovery process

    Energy Technology Data Exchange (ETDEWEB)

    Dzadzic, P.M.; Price, M.C.; Shih, C.J.; Weil, T.A.


    A process for production and recovery of hydrocarbons from hydrocarbon-containing whole plants in a form suitable for use as chemical feedstocks or as hydrocarbon energy sources which process comprises: (A) pulverizing by grinding or chopping hydrocarbon-containing whole plants selected from the group consisting of euphorbiaceae, apocynaceae, asclepiadaceae, compositae, cactaceae and pinaceae families to a suitable particle size, (B) drying and preheating said particles in a reducing atmosphere under positive pressure (C) passing said particles through a thermal conversion zone containing a reducing atmosphere and with a residence time of 1 second to about 30 minutes at a temperature within the range of from about 200* C. To about 1000* C., (D) separately recovering the condensable vapors as liquids and the noncondensable gases in a condition suitable for use as chemical feedstocks or as hydrocarbon fuels.

  5. Effect Of Hot Water Injection On Sandstone Permeability

    DEFF Research Database (Denmark)

    Rosenbrand, Esther; Fabricius, Ida Lykke


    The seasonal imbalance between supply and demand of renewable energy requires temporary storage, which can be achieved by hot water injection in warm aquifers. This requires that the permeability and porosity of the aquifer are not reduced significantly by heating. We present an overview...... of published results regarding the effect of temperature on sandstone permeability. These tests are performed with mineral oil, nitrogen gas, distilled water and solutions of NaCl, KCl, CaCl2 as well as brines that contain a mixture of salts. Thirteen sandstone formations, ranging from quartz arenites...... not account for all the permeability reductions observed. Permeablity reduction occurs both when distilled water is the saturating fluid as well as in tests with NaCl, KCl or CaCl2 solutions, however, this is not the case in tests with mineral oil or nitrogen gas. The formation of a filter cake or influx...

  6. Comparative study between Botucatu and Berea sandstone properties (United States)

    Cardoso, Oldemar Ribeiro; Balaban, Rosangela de Carvalho


    The aim of the present study is the analysis and comparison between Berea and Botucatu sandstone, concerning the problems with regard to the loss of permeability or water sensitivity or loss of hydraulic conductivity due to the presence of swelling or non-swelling clays. Some porous volumes of synthetic seawater of different salinities were displaced through the porous media of Berea and Botucatu formations. It was observed that even the plugs of Berea, with no-swelling clays in their composition, had the permeability reduced as soon as the brine salinity reached a lower limit. As expected, the same occurred with the Botucatu sandstone samples, however, in this case,the sensitivity to the low salinity was much more effective.

  7. Study of microwave response of coal and sandstone samples (United States)

    Singh, R.; Singh, Ramesh P.; Singh, K. P.


    Detailed measurements of relative dielectric constant and loss tangent of coal and sandstone samples have been carried out in the X-band of microwave frequency range (8-10 GHz). The effect of moisture, saline and petrol content on the dielectric and loss tangent has been studied. The reflection and transmission coefficient of these samples have been computed. The application of such measurements to geophysical prospecting has been discussed.

  8. Geological and petrophysical characterization of the ferron sandstone for 3-D simulation of a fluvial-deltaic reservoir. Annual report, October 1, 1994--September 30, 1995

    Energy Technology Data Exchange (ETDEWEB)

    Chidsey, T.C. Jr.; Allison, M.L.


    The objective of the Ferron Sandstone project is to develop a comprehensive, interdisciplinary, quantitative characterization of a fluvial-deltaic reservoir to allow realistic interwell and reservoir-scale models to be developed for improved oil-field development in similar reservoirs world-wide. Quantitative geological and petrophysical information on the Cretaceous Ferron Sandstone in east-central Utah was collected. Both new and existing data is being integrated into a three-dimensional model of spatial variations in porosity, storativity, and tensorial rock permeability at a scale appropriate for inter-well to regional-scale reservoir simulation. Simulation results could improve reservoir management through proper infill and extension drilling strategies, reduction of economic risks, increased recovery from existing oil fields, and more reliable reserve calculations. Transfer of the project results to the petroleum industry is an integral component of the project. This report covers research activities for fiscal year 1994-95, the second year of the project. Most work consisted of developing field methods and collecting large quantities of existing and new data. We also continued to develop preliminary regional and case-study area interpretations. The project is divided into four tasks: (1) regional stratigraphic analysis, (2) case studies, (3) reservoirs models, and (4) field-scale evaluation of exploration strategies.

  9. Geological and petrophysical characterization of the Ferron Sandstone for 3-D simulation of a fluvial-deltaic reservoir. Quarterly report, July 1--September 30, 1997

    Energy Technology Data Exchange (ETDEWEB)

    Allison, M.L.


    The objective of this project is to develop a comprehensive, interdisciplinary, and quantitative characterization of a fluvial-deltaic reservoir which will allow realistic inter-well and reservoir-scale modeling to be constructed for improved oil-field development in similar reservoirs world-wide. The geological and petrophysical properties of the Cretaceous Ferron Sandstone in east-central Utah will be quantitatively determined. Both new and existing data will be integrated into a three-dimensional representation of spatial variations in porosity, storativity, and tensorial rock permeability at a scale appropriate for inter-well to regional-scale reservoir simulation. Results could improve reservoir management through proper infill and extension drilling strategies, reduction of economic risks, increased recovery from existing oil fields, and more reliable reserve calculations. Two activities continued this quarter as part of the geological and petrophysical characterization of the fluvial-deltaic Ferron Sandstone: (1) evaluation of the Ivie Creek and Willow Springs Wash case-study areas and (2) technology transfer.

  10. Dinosaur ichnofauna of the Upper Jurassic/Lower Cretaceous of the Paraná Basin (Brazil and Uruguay) (United States)

    Francischini, H.; Dentzien–Dias, P. C.; Fernandes, M. A.; Schultz, C. L.


    Upper Jurassic and Lower Cretaceous sedimentary layers are represented in the Brazilian Paraná Basin by the fluvio-aeolian Guará Formation and the Botucatu Formation palaeoerg, respectively, overlapped by the volcanic Serra Geral Formation. In Uruguay, the corresponding sedimentary units are named Batoví and Rivera Members (both from the Tacuarembó Formation), and the lava flows constitute the Arapey Formation (also in Paraná Basin). Despite the lack of body fossils in the mentioned Brazilian formations, Guará/Batoví dinosaur fauna is composed of theropod, ornithopod and wide-gauge sauropod tracks and isolated footprints, as well as theropod teeth. In turn, the Botucatu/Rivera dinosaur fauna is represented by theropod and ornithopod ichnofossils smaller than those from the underlying units. The analysis of these dinosaur ichnological records and comparisons with other global Mesozoic ichnofauna indicates that there is a size reduction in dinosaur fauna in the more arid Botucatu/Rivera environment, which is dominated by aeolian dunes. The absence of sauropod trackways in the Botucatu Sandstone fits with the increasingly arid conditions because it is difficult for heavy animals to walk on sandy dunes, as well as to obtain the required amount of food resources. This comparison between the Upper Jurassic and Lower Cretaceous dinosaur fauna in south Brazil and Uruguay demonstrates the influence of aridization on the size of animals occupying each habitat.

  11. Unroofing of the Gangdese arc as documented in the Cretaceous succession of the Xigaze forearc basin (South Tibet) (United States)

    An, Wei; Hu, Xiumian; Wang, Jiangang; Garzanti, Eduardo


    The Xigaze forearc basin formed in the Cretaceous, between the Yalung-Zangbo suture zone to the south and the Gangdese arc to the north, during subduction of Neo-Tethyan oceanic lithosphere under the Lhasa terrane (Einsele et al., 1994; Durr, 1996; Wang et al., 1999, 2012; Wu et al., 2010). Well-preserved and superbly exposed strata provide an excellent opportunity to study the evolution of a forearc basin. The succession includes the Sangzugang, Chongdui, Ngmaring and Padana Formations (from bottom to top). The Sangzugang Fm. accumulated as a carbonate platform on the southern Lhasa margin in the Aptian- Early Albian (~120-107 Ma), while cherts of the lower Chongdui Fm. were deposited on the continental rise. In the Late Albian- Cenomanian (~107-98 Ma), turbiditic sandstones were deposited in distal-fan (lower-middle Chongdui sandstones) to slope settings (lower Ngmaring Fm.). The upper Ngmaring and Padana Fms. (Late Cenomanian- Early Campanian, 98-77 Ma) document a shallowing-upward succession deposited in submarine-fan, shelfal and finally deltaic environments, recording the transition from the underfilled stage (Aptian-Coniacian; ~120-86 Ma), to the filled stage (Santonian-Campanian; 86-77 Ma). Sandstone composition evolves from feldspatho-lithic arenite to litho-feldspatho-quartzose and finally litho-quartzose, indicating a change from undissected to dissected arc and finally mixed provenance. Detrital zircons from the upper Chongdui and lower-middle Ngmaring Fms. yielded dominantly Mesozoic ages, passing upward from unimodal (peak age at 110 Ma) to bimodal distribution (peak ages at ~110 and ~158 Ma). Age patterns are more complex in the upper Ngmaring and Padana Formations, with many pre-Mesozoic ages and more clusters of Mesozoic ages. Our dataset indicates volcanic and next plutonic rocks of the Gangdese arc as the main source of sediments in the early forearc-basin stage. Erosion of the Lhasa block later on attested to the final unroofing stage of the

  12. Strength and elastic properties of sandstone under different testing conditions

    Institute of Scientific and Technical Information of China (English)

    CHEN Yun-ping; WANG Si-jing; WANG En-zhi


    A laboratory experimental program performed on Wuhan sandstones was presented under monotonic loading, partial cyclic loading during loading path and sine wave cyclic loading with different strain rates to compare uniaxial compression strength and elastic properties (elastic modulus and Poisson ratio) under different conditions and influence of pore fluid on them. When the loading strain rates are 10-5, 10-4 and 10-3/s, uniaxial compression strengths of dry sandstones are 82.3, 126.6 and 141.6 MPa,respectively, and that of water saturated sandstones are 70.5, 108.3 and 124.1 MPa, respectively. The above results show that the uniaxial compression strength increases with the increase of strain rate, however, variation of softening coefficient is insignificant.Under monotonic loading condition, tangent modulus increases with an increment of stress (strain) to a maximum value at a certain stress level, beyond which it starts to decline. Under the partial cyclic loading during loading path condition, unloading or reloading modulus is larger than loading modulus, and unloading and reloading moduli are almost constants with respect to stress level,especially unloading modulus. Under the sine wave cyclic loading condition, tangent modulus and Poisson ratio display asymmetric 'X' shape with various strain, and the average unloading modulus is larger than the average loading modulus.

  13. Calcium lignosulfonate adsorption and desorption on Berea sandstone. (United States)

    Grigg, Reid B; Bai, Baojun


    This paper describes adsorption and desorption studies carried out with calcium lignosulfonate (CLS) on Berea sandstone. Circulation experiments were performed to determine CLS adsorption isotherms and the effects of CLS concentration, temperature, salinity, brine hardness, and injection rate on adsorption density. Flow-through experiments were performed to assess the reversibility of CLS adsorption and the influence of postflush rate, brine concentration, brine hardness, brine pH, and temperature on the desorption process. Results indicate that CLS adsorption isotherms on Berea sandstone follow the Freundlich isotherm law. The results presented in this paper on the effects of CLS adsorption and desorption on Berea sandstone show that: (1) increasing CLS concentration and salinity increases CLS adsorption density; (2) increasing temperature will decrease adsorption density; (3) increasing injection rate of CLS solution will slightly decrease CLS adsorption density; (4) postflush rate and salinity of brine have a large impact on the CLS desorption process; (5) the adsorption and desorption process are not completely reversible; and (5) temperature and pH of the postflush brine have little effect on desorption.

  14. Fossil worm burrows reveal very early terrestrial animal activity and shed light on trophic resources after the end-cretaceous mass extinction.

    Directory of Open Access Journals (Sweden)

    Karen Chin

    Full Text Available The widespread mass extinctions at the end of the Cretaceous caused world-wide disruption of ecosystems, and faunal responses to the one-two punch of severe environmental perturbation and ecosystem collapse are still unclear. Here we report the discovery of in situ terrestrial fossil burrows from just above the impact-defined Cretaceous-Paleogene (K/Pg boundary in southwestern North Dakota. The crisscrossing networks of horizontal burrows occur at the interface of a lignitic coal and silty sandstone, and reveal intense faunal activity within centimeters of the boundary clay. Estimated rates of sedimentation and coal formation suggest that the burrows were made less than ten thousand years after the end-Cretaceous impact. The burrow characteristics are most consistent with burrows of extant earthworms. Moreover, the burrowing and detritivorous habits of these annelids fit models that predict the trophic and sheltering lifestyles of terrestrial animals that survived the K/Pg extinction event. In turn, such detritus-eaters would have played a critical role in supporting secondary consumers. Thus, some of the carnivorous vertebrates that radiated after the K/Pg extinction may owe their evolutionary success to thriving populations of earthworms.

  15. First record of Ephemeropsis, Coptoclava, Coleoptera inc. sed. and Turfanograpta from Lower Cretaceous paper-shales of the western-most site of Mongolia

    Directory of Open Access Journals (Sweden)

    H. Jähnichen


    Full Text Available Nymph-fragments (and detached cerci of the may-fly Ephemeropsis trisetalis Eichwald and the water-beetle Coptoclava longipoda Ping, a coleopteran and a shell-fragment of the conchostracan Turfanograpta sp. are described for the first time from Lower Cretaceous paper-shales of Bajan-Khongor, Mongolia. The assemblage Lycoptera (fishes included in the Order Osteoglossiformes, Fam. Lycopteridae-Ephemeropsis-Coptoclava correlates with Lower Cretaceous deposits in Transbaikalia, Mongolia and North-Eastern China. The fern-species Adiantopteris sewardi (Yabe Vassiljevskaja and Adiantopteris toyoraënsis (Oishi Vassiljevskaja occur in fine-sandstones of Bajan-Khongor (Jähnichen & Kahlert 1972. Their importance as Early Cretaceous flora-elements is discussed. Larvenfragmente und isolierte Cerci der Eintagsfliege Ephemeropsis trisetalis Eichwald und vom Wasserkäfer Coptoclava longipoda Ping, und ein Schalenfragment der Conchostrake Turfanograpta sp. werden erstmalig aus unterkretazischen Dysodilen von Bajan-Khongor in der Mongolei beschrieben. Die Faunengemeinschaft Lycoptera (Fische der Ordnung Osteoglossiformes, Fam. Lycopteridae-Ephemeropsis-Coptoclava tritt gleichzeitig in unterkretazischen Ablagerungen von Transbaikalien, Mongolei, und im nordöstlichen China auf. Das Vorkommen der Farnspezies Adiantopteris sewardi (Yabe Vassil-jevskaja und Adiantopteris toyoraënsis (Oishi Vassiljevskaja in Feinsandsteinen von Bajan-Khongor (Jähnichen & Kahlert 1972 und deren Wichtigkeit als unterkretazische Florenelemente werden diskutiert. doi:10.1002/mmng.20000030104

  16. The late Cenomanian oyster Lopha staufferi (Bergquist, 1944) - the oldest ribbed oyster in the Upper Cretaceous of the Western Interior of the United States (United States)

    Hook, Stephen C.; Cobban, William A.


    Lopha staufferi (Bergquist, 1944) is a medium-sized, ribbed, Late Cretaceous oyster with a slightly curved axis and a zigzag commissure; it appears suddenly and conspicuously in upper Cenomanian rocks in the Western Interior Basin of the United States. At maturity, the ribs on both valves thicken into steep flanks that allow the oyster to increase interior volume without increasing its exterior footprint on the seafloor. Lopha staufferi is the first (earliest) ribbed oyster in the Late Cretaceous of the Western Interior, but has no ancestor in the basin. It disappears from the rock record as suddenly as it appeared, leaving no direct descendent in the basin. In the southern part of the basin where it is well constrained, L. staufferi is restricted stratigraphically to the upper Cenomanian Metoicoceras mosbyense Zone (= Dunveganoceras conditum Zone in the north). Lopha staufferi has an unusual paleogeographic distribution, occurring in only two, widely scattered areas in the basin. It has been found at several localities near the western shoreline of the Late Cretaceous Seaway in west-central New Mexico and adjacent Arizona, and in localities 1,900 km (1,200 mi) to the northeast near the eastern shoreline in northeastern Minnesota, but nowhere in between. In west-central New Mexico and adjacent Arizona, L. staufferi is a guide fossil to the Twowells Tongue of the Dakota Sandstone.

  17. Fossil Worm Burrows Reveal Very Early Terrestrial Animal Activity and Shed Light on Trophic Resources after the End-Cretaceous Mass Extinction (United States)

    Chin, Karen; Pearson, Dean; Ekdale, A. A.


    The widespread mass extinctions at the end of the Cretaceous caused world-wide disruption of ecosystems, and faunal responses to the one-two punch of severe environmental perturbation and ecosystem collapse are still unclear. Here we report the discovery of in situ terrestrial fossil burrows from just above the impact-defined Cretaceous-Paleogene (K/Pg) boundary in southwestern North Dakota. The crisscrossing networks of horizontal burrows occur at the interface of a lignitic coal and silty sandstone, and reveal intense faunal activity within centimeters of the boundary clay. Estimated rates of sedimentation and coal formation suggest that the burrows were made less than ten thousand years after the end-Cretaceous impact. The burrow characteristics are most consistent with burrows of extant earthworms. Moreover, the burrowing and detritivorous habits of these annelids fit models that predict the trophic and sheltering lifestyles of terrestrial animals that survived the K/Pg extinction event. In turn, such detritus-eaters would have played a critical role in supporting secondary consumers. Thus, some of the carnivorous vertebrates that radiated after the K/Pg extinction may owe their evolutionary success to thriving populations of earthworms. PMID:23951041

  18. Paleogeography of the mid-Cretaceous period

    Energy Technology Data Exchange (ETDEWEB)

    Zharkov, M.A.; Murdmaa, I.O.; Filatova, N.I. [Russian Academy of Sciences, Moscow (Russian Federation)


    Global lithologic-paleogeographic maps for the Aptian, Albian, Cenomanian, and Turonian stages of the Cretaceous were compiled for the first time using common methods and taking into consideration the paleogeographic environment of continents and oceans. Particular features of the global distribution of arid and humid environments on continents were analyzed to distinguish belts and zones of evaporite and red-bed sedimentation, coal accumulation, and bauxite and kaolin formation. It is shown that climatic zonality and the location of arid and humid environments on continents were dependent on the arrangement of continents and oceans on the surface of the Earth.

  19. Compositional Trends of Cretaceous Conglomerate Provenance: Tracing The Evolving Nature of Tectonic Environments in the Northwestern Colombian Andes (United States)

    Patino, A. M.; Zapata, S.; Cardona, A.; Jaramillo, J. S.


    The composition and provenance of the sedimentary record is a sensible marker of the evolving nature of source , basin paleogeography and tectonic assemblage. The Cretaceous geological evolution of the northern Andes is characterized by the succession of different tectonic environments that include: An early Cretaceous magmatic quiescence that follow former Jurassic arc magmatism, Albian-Aptian subduction resume and associated arc - back-arc formation and the late Cretaceous collision with an allocthonous oceanic arc that marks the beginning of the Andean orogeny. Such tectonic evolution had been mostly reconstructed from the magmatic record or the stratigraphic analysis of inland basin far from the arcs and suture zones. Along the western flank of the central cordillera outcrops two different stratigraphic units with notable differences in the provenance and timing of accumulation. The Abejorral Formation is the oldest sedimentary sequence (Albian-Aptian) that discordantly overlies the Triassic continental margin. this unit include two lithofacies clearly distinguishable, a lithofacies consist mostly of conglomerate, characterized by abundant quartz content , low compaction, rounded clasts and moderate sorting ; and the other is a interbedded of fine size sandstone, mudstone and chert; also with abundant quartz content further muscovite, containing basement and volcanic material . To the west, sedimentary rocks including within the Quebradagrande Formation conform a turbidite sequence with a well defined Bouma type succession that concordantly overlied a Campanian marine volcanic arc succession. The conglomerates associated to this unit are characterized by containing mainly sedimentary and volcanic rock fragments ,high compaction, subrounded clast, and low sorting. This sequence is overlying by the volcanic component in a concord contact. Whereas the Albian-Aptian record of the Abejorral Formation exhibit the unroofing of the continental basement and deepening of

  20. Provenance and drainage system of the Early Cretaceous volcanic detritus in the Himalaya as constrained by detrital zircon geochronology

    Institute of Scientific and Technical Information of China (English)

    Xiu-Mian Hu; Eduardo Garzanti; Wei An


    The age range of the major intra-plate volcanic event that affected the northern Indian margin in the Early Cretaceous is here deifned precisely by detrital zircon geochronol-ogy. U–Pb ages of Early Cretaceous detrital zircons found in the Cretaceous to the Paleocene sandstones cluster mainly between 142 Ma and 123 Ma in the northern Tethys Himalayan unit, and between 140 Ma and 116 Ma in the southern Tethys Himalayan unit. The youngest and oldest detrital zircons within this group indicate that volcanism in the source areas started in the latest Jurassic and ended by the early Albian. Stratigraphic data indicate that volcaniclastic sedimentation began signiifcantly earlier in southern Tibet (Tithonian) than in Nepal (Valangin-ian), and considerably later in Spiti and Zanskar (Aptian/Albian) to the west. This apparent westward migration of magmatism was explained with progressive westward propagation of extensional/transtensional tectonic activity and development of fractures cutting deeply across the Indian continental margin crust. However, detrital zircon geochronology provides no indi-cation of heterochroneity in magmatic activity in the source areas from east to west, and thus lends little support to such a scenario. Westward migration of volcaniclastic sedimentation may thus relfect instead the westward progradation of major drainage systems supplying vol-canic detritus sourced from the same volcanic centers in the east. Development of multiple radial drainage away from the domal surface uplift associated with magmatic upwelling, as observed for most large igneous provinces around the world, may also explain why U–Pb ages of detrital zircons tend to cluster around 133–132 Ma (the age of the Comei igneous province) in Tethys Himalayan units, but around 118–117 Ma (the age of the Rajmahal igneous province) in Lesser Himalayan units.

  1. Experimental deformation in sandstone, carbonates and quartz aggregate

    Energy Technology Data Exchange (ETDEWEB)

    Cheung, Cecilia See Nga [Stony Brook Univ., NY (United States)


    The first part of my thesis is mainly focused on the effect of grain size distribution on compaction localization in porous sandstone. To identify the microstructural parameters that influence compaction band formation, I conducted a systematic study of mechanical deformation, failure mode and microstructural evolution in Bleurswiller and Boise sandstones, of similar porosity (~25%) and mineralogy but different sorting. Discrete compaction bands were observed to develop over a wide range of pressure in the Bleurswiller sandstone that has a relatively uniform grain size distribution. In contrast, compaction localization was not observed in the poorly sorted Boise sandstone. My results demonstrate that grain size distribution exerts important influence on compaction band development, in agreement with recently published data from Valley of Fire and Buckskin Gulch, as well as numerical studies. The second part aimed to improve current knowledge on inelastic behavior, failure mode and brittle-ductile transition in another sedimentary rock, porous carbonates. A micritic Tavel (porosity of ~13%) and an allochemical Indiana (~18%) limestones were deformed under compaction in wet and dry conditions. At lower confining pressures, shear localization occurred in brittle faulting regime. Through transitional regime, the deformation switched to cataclastic flow regime at higher confining pressure. Specifically in the cataclastic regime, the (dry and wet) Tavel and dry Indiana failed by distributed cataclastic flow, while in contrast, wet Indiana failed as compaction localization. My results demonstrate that different failure modes and mechanical behaviors under different deformation regimes and water saturation are fundamental prior to any geophysical application in porous carbonates. The third part aimed to focus on investigating compaction on quartz aggregate starting at low (MPa) using X-ray diffraction. We report the diffraction peak evolution of quartz with increasing


    Directory of Open Access Journals (Sweden)



    Full Text Available Fragmentary cranial bones of dinosaur origin have been recently recovered from the Kem Kem beds (Upper Cretaceous, Cenomanian of Morocco. They include two incompletely preserved maxillary bones evidencing diagnostic features of abelisaurid theropods. These new finds provide further evidence of Abelisauridae in the Late Cretaceous of Morocco. 

  3. A plate tectonic-paleoceanographic hypothesis for Cretaceous source rocks and cherts of northern South America

    Energy Technology Data Exchange (ETDEWEB)

    Villamil, T.; Arango, C. (Univ. of Colorado, Boulder, CO (United States))


    New paleocontinental reconstructions show a northern migration of the South American Plate with respect to the paleoequator from the Jurassic to the Late Cretaceous. This movement caused the northern margin of South America to migrate from a position south to a position north of the paleoequator. Ekman transport generated net surface water movement towards the south during times when northern South America was south of the paleoequator. This situation favored downwelling and prevented Jurassic and earliest Cretaceous marine source rocks from being deposited. When northern South America was north of the paleoequator Ekman transport forced net water movement to the north favoring upwelling, paleoproductivity, and the deposition of one of the best marine source rocks known (the La Luna, Villeta, and equivalents). This plate tectonic paleoceanographic hypothesis explains the origin of hydrocarbons in northern South America. The stratigraphic record reflects this increase in paleoproductivity through time. This can be observed in facies (non-calcareous shales to calcareous shales to siliceous shales and finally to bedded cherts) and in changing planktic communities which were initially dominated by healthy calcareous foraminifer assemblages, followed by stressed foraminifer populations and finally by radiolarians. Total organic carbon and source rock quality were affected by this long term increase in paleoproductivity but also, and more markedly, by a punctuated sequence stratigraphic record dominated by low- frequency changes in relative sea level. The magnitude of transgressive episodes caused by rise in sea level determined the extent of source rock intervals and indirectly the content of organic carbon.

  4. A plate tectonic-paleoceanographic hypothesis for Cretaceous source rocks and cherts of northern South America

    Energy Technology Data Exchange (ETDEWEB)

    Villamil, T.; Arango, C. [Univ. of Colorado, Boulder, CO (United States)


    New paleocontinental reconstructions show a northern migration of the South American Plate with respect to the paleoequator from the Jurassic to the Late Cretaceous. This movement caused the northern margin of South America to migrate from a position south to a position north of the paleoequator. Ekman transport generated net surface water movement towards the south during times when northern South America was south of the paleoequator. This situation favored downwelling and prevented Jurassic and earliest Cretaceous marine source rocks from being deposited. When northern South America was north of the paleoequator Ekman transport forced net water movement to the north favoring upwelling, paleoproductivity, and the deposition of one of the best marine source rocks known (the La Luna, Villeta, and equivalents). This plate tectonic paleoceanographic hypothesis explains the origin of hydrocarbons in northern South America. The stratigraphic record reflects this increase in paleoproductivity through time. This can be observed in facies (non-calcareous shales to calcareous shales to siliceous shales and finally to bedded cherts) and in changing planktic communities which were initially dominated by healthy calcareous foraminifer assemblages, followed by stressed foraminifer populations and finally by radiolarians. Total organic carbon and source rock quality were affected by this long term increase in paleoproductivity but also, and more markedly, by a punctuated sequence stratigraphic record dominated by low- frequency changes in relative sea level. The magnitude of transgressive episodes caused by rise in sea level determined the extent of source rock intervals and indirectly the content of organic carbon.

  5. Origination and death of petroleum systems along the Late Jurassic/Early Cretaceous northern Tethyan margin

    Energy Technology Data Exchange (ETDEWEB)

    Golonka, J. [Mobil Research and Development Corp., Dallas, TX (United States); Kiessling, W. [Erlangen-Nuernberg Univ., Erlangen (Germany). Inst. fuer Geologie und Mineralogie; Krobicki, M. [Academy of Mining and Metallurgy, Cracow (Poland). Inst. of Petroleum Engineering; Bocharova, N.Y. [Russian Academy of Sciences, Moscow (Russian Federation). Center for Program Studies


    Breakup of Pangea during Jurassic and Cretaceous times created a system of rifts along the northern Tethyan margin. Some of these rifts developed into oceanic basins while others developed on continental crust and turned into aulacogenes. The basins were separated from the main Tethys ocean by several plates and ridges. Partial uplift of the main European plate and late Kimmerian orogeny resulted in the establishment of restricted conditions in the marginal Tethyan basins. The paleogeographic and paleoclimatic setting favoured upwelling along the ridges and continental margins. Source rock prediction value modelling placed Tethyan marginal basins among the best Jurassic source rocks of the world. Self-contained petroleum systems consisting of source rocks, carbonate reservoirs and evaporitic seals occur in the area east of Poland. Actual hydrocarbon production is ongoing in Afghanistan and the Amu-Daria province. Some of Carpathian oils might also be sourced by Late Jurassic/Early Cretaceous rocks. In the western area, petroleum systems were destroyed during the Alpine orogeny.

  6. Criteria for recognition of localization and timing of multiple events of hydrothermal alteration in sandstones illustrated by petrographic, fluid inclusion, and isotopic analysis of the Tera Group, Northern Spain (United States)

    González-Acebrón, Laura; Goldstein, R. H.; Mas, Ramón; Arribas, José


    Stratigraphic relations, detailed petrography, microthermometry of fluid inclusions, and fine-scale isotopic analysis of diagenetic phases indicate a complex thermal history in Tithonian fluvial sandstones and lacustrine limestones of the Tera Group (North Spain). Two different thermal events have been recognized and characterized, which are likely associated with hydrothermal events that affected the Cameros Basin during the mid-Cretaceous and the Eocene. Multiple stages of quartz cementation were identified using scanning electron microscope cathodoluminescence on sandstones and fracture fills. Primary fluid inclusions reveal homogenization temperatures (Th) from 195 to 350°C in the quartz cements of extensional fracture fillings. The high variability of Th data in each particular fluid inclusion assemblage is related to natural reequilibration of the fluid inclusions, probably due to Cretaceous hydrothermal metamorphism. Some secondary fluid inclusion assemblages show very consistent data (Th = 281-305°C) and are considered not to have reequilibrated. They are likely related to an Eocene hydrothermal event or to a retrograde stage of the Cretaceous hydrothermalism. This approach shows how multiple thermal events can be discriminated. A very steep thermal gradient of 97-214°C/km can be deduced from δ18O values of ferroan calcites (δ18O -14.2/-11.8‰ V-PDB) that postdate quartz cements in fracture fillings. Furthermore, illite crystallinity data (anchizone-epizone boundary) are out of equilibrium with high fluid inclusion Th. These observations are consistent with heat-flux related to short-lived events of hydrothermal alteration focused by permeability contrasts, rather than to regional heat-flux associated with dynamo-thermal metamorphism. These results illustrate how thermal data from fracture systems can yield thermal histories markedly different from host-rock values, a finding indicative of hydrothermal fluid flow.

  7. Seismic modeling, rock physics, avo and seismic attribute analysis for illuminating sandstone facies of the Late Ordovic Ian Mamuniyat Reservoir, R-Field, Murzuq Basin-Libya (United States)

    Abushalah, Yousf Milad

    The Late Ordovician Mamuniyat Formation is the main hydrocarbon reservoir in the R-Field in Murzuq Basin, SW Libya. The Lower Mamuniyat, which is the only unit that was encountered in the study area, is composed of sandstone facies called Clean Mamuniyat and shaly sandstone facies called Dirty Mamuniyat. One major problem with the development of the R-Field is the difficulty of distinguishing the two units so this project was aimed to develop better methods for distinguishing between the two units of the Lower Mamuniyat. The other problem is to distinguish the transgressive shaly facies of the Bir Tlacsin, which has an impact on the hydrocarbon accumulation. Those issues manifested in limit of seismic resolution and interference that resulted from the converted shear mode waves. The dissertation was divided into three chapters. In the first chapter, seismic modeling using a deterministic and a Ricker wavelet were used to investigate the interference effects on the poststack seismic data and a bandpass filter was used to remove those effects. Instantaneous frequency, spectral-based colored inversion and rock physics were, then applied to determine the distributions of the sandstone facies of the Lower Mamuniyat Formation and to interpret the depositional setting of it. In the second chapter, spectral decomposition and inverted density were utilized to determine the distribution of the shaly facies of Bir Tlacsin, and its temporal thickness and to remap the top reservoir. In the last chapter, amplitude variation with offset (AVO) modeling, ray tracing, and spectral analysis were used to investigate the mode conversion and its effect on AVO signature, the amplitude of the near-mid and far offsets and frequency contents. Data enhancement then was performed using partial stacks and a bandpass filter.

  8. Cretaceous-Palaeogene experiments in Biogeochemical Resilience (United States)

    Penman, D. E.; Henehan, M. J.; Hull, P. M.; Planavsky, N.; Schmidt, D. N.; Rae, J. W. B.; Thomas, E.; Huber, B. T.


    Human activity is altering biogeochemical cycles in the ocean. While ultimately anthropogenic forcings may be brought under control, it is still unclear whether tipping points may exist beyond which human-induced changes to biogeochemical cycles become irreversible. We use the Late Cretaceous and the Cretaceous-Palaeogene (K-Pg) boundary interval as an informative case study. Over this interval, two carbon cycle perturbations (gradual flood basalt volcanism and abrupt bolide impact) occurred within a short time window, allowing us to investigate the resilience of biogeochemical cycles to different pressures applied to the same initial boundary conditions on very different time scales. We demonstrate that relatively gradual emission of CO2 from the Deccan large igneous province was efficiently mitigated within the limits of existing biogeochemical processes. However, the rapid extinction of pelagic calcifying organisms at the K-Pg boundary due to the Chicxulub bolide impact had more profound effects, and caused lasting (> 1 million years) changes to biogeochemical cycles. By combining sedimentological observations with boron isotope-based pH reconstructions over these events, we document two potentially useful partial analogues for best and worst case scenarios for anthropogenic global change. We suggest that if current ocean acidification results in the mass extinction of marine pelagic calcifiers, we may cause profound changes to the Earth system that will persist for 100,000s to millions of years.

  9. Tectonic repetitions of the Early Cretaceous Agrio Formation in the Chos Malal fold-and-thrust belt, Neuquén Basin, Argentina: Geometry, kinematics and structural implications for Andean building (United States)

    Turienzo, M.; Sánchez, N.; Dimieri, L.; Lebinson, F.; Araujo, V.


    The Neuquén Basin, developed in a retroarc setting in the central-west of Argentina, contains more than 6000 m of Mesozoic marine and continental sedimentary rocks. These rocks were deformed during the Andean orogeny leading to several thick and thin-skinned fold-and-thrust belts. The Early Cretaceous Agrio Formation is composed by a thick marine succession predominantly of black shales in which highlights a thin fluvial-aeolian sandy interval named Avilé Member. The Avilé Member, one of the most important hydrocarbon reservoirs of the Neuquén Basin, constitutes an excellent structural marker. At the Chos Malal fold-and-thrust belt, the strong mechanical anisotropy given by the contrasting lithology of the Avilé Member within the Agrio Formation favored the location of detachments along the shales and ramps affecting the sandstones during the Andean compression. Detailed field mapping at the Chacay Melehue area allowed us to recognize tectonic repetitions of the Avilé Member, which form imbrications in the simplest case whereas in other places constitute a more complex combination of imbrications, including fault-bend folding that duplicates stratigraphic sequences and fault-propagation folding that deforms more intensely the duplicated units. Along three structural cross-sections we illustrate the geometry of these tectonic repetitions of the Agrio Formation, which in the northern area have an eastward-vergence and in the central and southern regions show a clear westward-vergence. A tear fault along the arroyo Chacay Melehue could explain this vergence change. Forward modeling of the structures at the central cross-section, where a backthrust system produced imbrication, duplication and folding of the Agrio Formation, allows us to propose a balanced kinematic reconstruction of this complex structure and to compare the features produced at different stages of the deformation sequence with field observations. Our kinematic interpretation shows that the

  10. Mechanical Weakening during Fluid Injection in Critically Stressed Sandstones with Acoustic Monitoring (United States)

    David, C.; Dautriat, J. D.; Sarout, J.; Macault, R.; Bertauld, D.


    Water weakening is a well-known phenomenon which can lead to subsidence during the production of hydrocarbon reservoirs. The example of the Ekofisk oil field in the North Sea has been well documented for years. In order to assess water weakening effects in reservoir rocks, previous studies have focused on changes in the failure envelopes derived from mechanical tests conducted on rocks saturated either with water or with inert fluids. However, little attention has been paid so far on the mechanical behaviour during the fluid injection stage, like in enhanced oil recovery operations. We studied the effect of fluid injection on the mechanical behaviour of Sherwood sandstone, a weakly-consolidated sandstone sampled at Ladram Bay in UK. In order to highlight possible weakening effects, water and inert oil have been injected into critically-loaded samples to assess their effect on strength and elastic properties and to derive the acoustic signature of the saturation front for each fluid. The specimens were instrumented with 16 ultrasonic P-wave transducers for both passive and active acoustic monitoring during fluid injection and loading. After conducting standard triaxial tests on three samples saturated with air, water and oil respectively, mechanical creep tests were conducted on dry samples loaded at 80% of the compressive strength of the dry rock. While these conditions are kept constant, a fluid is injected at the bottom end of the sample with a low back pressure (0.5 MPa) to minimize effective stress variations during injection. Both water and oil were used as the injected pore fluid in two experiments. As soon as the fluids start to flow into the samples, creep is taking place with a much higher strain rate for water injection compared to oil injection. A transition from secondary creep to tertiary creep is observed in the water injection test whereas in the oil injection test no significant creep acceleration is observed after one pore volume of oil was

  11. Tunasniyoj, a dinosaur tracksite from the Jurassic-Cretaceous boundary of Bolivia. (United States)

    Apesteguía, Sebastián; Gallina, Pablo A


    Here we report a superbly preserved and profusely represented five-ichnotaxa dinosaur track assemblage near Icla village, 100 km southeast of Sucre, Bolivia. As preserved in reddish Jurassic-Cretaceous boundary aeolian sandstones, this rich and uncommon assemblage is, additionally, the oldest dinosaur tracksite for Bolivia. Four trackmakers were identified in the area: three quadrupedal and one bipedal, all of them with tracks of around 35 cm in lenght. One of the quadrupedals is represented by no less than five adult individuals (ichnotaxon A), and four purported juveniles (ichnotaxon B) walking in association. The other two quadrupedals (ichnotaxa C and D) involve four trackways, and the last, the bipedal trackmaker (ichnotaxon E), is represented by one trackway. The five ichnotaxa represented in the "Palmar de Tunasniyoj" could be tentatively assigned to the following trackmakers: Ichnotaxa A and B are assigned to basal stegosaurians; ichnotaxon C to a basal tyreophoran, perhaps related to the ankylosaur lineage; ichnotaxon D to the Ankylosauria, and ichnotaxon E to Theropoda. The Tunasniyoj assemblage, the oldest dinosaur tracksite for Bolivia, includes the oldest known evidence assigned to ankylosaurs and stegosaurs for South America.

  12. Plesiosaur-bearing rocks from the Late Cretaceous Tahora Fm, Mangahouanga, New Zealand - a palaeoenvironmental study (United States)

    Vajda, Vivi; Raine, J. Ian


    Mangahouanga Stream, Hawkes Bay, New Zealand is world-famous for its high southern latitude vertebrate fossils including plesiosaurs, mosasaurs and more rarely, dinosaurs. The fossils are preserved in the conglomeratic facies of the Maungataniwha Sandstone Member of the Tahora Formation. A palynological investigation of sediments from the boulders hosting vertebrate fossils reveals well-preserved palynological assemblages dominated by pollen and spores from land plants but also including marine dinoflagellate cysts in one sample. The palynofacies is strongly dominated by wood fragments including charcoal, and the sample taken from a boulder hosting plesiosaur vertebrae is entirely terrestrially derived, suggesting a fresh-water habitat for at least some of these plesiosaurs. The key-pollen taxa Nothofagidites senectus and Tricolpites lilliei, together with the dinocyst Isabelidinium pellucidum and the megaspore Grapnelispora evansii, strongly indicate an early Maastrichtian age for the host rock. The terrestrial palynoflora reflects a mixed vegetation dominated by podocarp conifers and angiosperms with a significant tree-fern subcanopy component. The presence of taxa with modern temperate distributions such as Nothofagus (southern beech), Proteaceae and Cyatheaceae (tree-ferns), indicates a mild-temperate climate and lack of severe winter freezing during the latest Cretaceous, providing an ecosystem which most probably made it possible for polar dinosaurs to overwinter. The paper is dedicated to Mrs Joan Wiffen who with her great persistence, enthusiasm and courage put Mangahouanga on the world map, becoming a role model for many young scientists.

  13. Thraustochytrid protists degrade hydrocarbons

    Digital Repository Service at National Institute of Oceanography (India)

    Raikar, M.T.; Raghukumar, S.; Vani, V.; David, J.J.; Chandramohan, D.

    Although thraustochytrid protists are known to be of widespread occurrence in the sea, their hydrocarbon-degrading abilities have never been investigated. We isolated thraustochytrids from coastal waters and sediments of Goa coast by enriching MPN...

  14. Composition of natural gas and crude oil produced from 10 wells in the Lower Silurian "Clinton" Sandstone, Trumbull County, Ohio: Chapter G.7 in Coal and petroleum resources in the Appalachian basin: distribution, geologic framework, and geochemical character (United States)

    Burruss, Robert A.; Ryder, Robert T.; Ruppert, Leslie F.; Ryder, Robert T.


    Natural gases and associated crude oils in the “Clinton” sandstone, Medina Group sandstones, and equivalent Tuscarora Sandstone in the northern Appalachian basin are part of a regional, continuous-type or basin-centered accumulation. The origin of the hydrocarbon charge to regional continuoustype accumulations is poorly understood. We have analyzed the molecular and stable isotopic composition of gases and oils produced from 10 wells in the “Clinton” sandstone in Trumbull County, Ohio, in an initial attempt to identify the characteristics of the accumulated fluids. The analyses show that the fluids have remarkably uniform compositions that are similar to previously published analyses of oils (Cole and others, 1987) and gases (Laughrey and Baldasarre, 1998) in Early Silurian reservoirs elsewhere in Ohio; however, geochemical parameters in the oils and gases suggest that the fluids have experienced higher levels of thermal stress than the present-day burial conditions of the reservoir rocks. The crude oils have an unusual geochemical characteristic: they do not contain detectable levels of sterane and triterpane biomarkers. The origin of these absences is unknown.

  15. Composition of natural gas and crude oil produced from 10 wells in the Lower Silurian "Clinton" Sandstone, Trumbull County, Ohio: Chapter G.7 in Coal and petroleum resources in the Appalachian basin: distribution, geologic framework, and geochemical character (United States)

    Burruss, Robert A.; Ryder, Robert T.; Ruppert, Leslie F.; Ryder, Robert T.


    Natural gases and associated crude oils in the “Clinton” sandstone, Medina Group sandstones, and equivalent Tuscarora Sandstone in the northern Appalachian basin are part of a regional, continuous-type or basin-centered accumulation. The origin of the hydrocarbon charge to regional continuoustype accumulations is poorly understood. We have analyzed the molecular and stable isotopic composition of gases and oils produced from 10 wells in the “Clinton” sandstone in Trumbull County, Ohio, in an initial attempt to identify the characteristics of the accumulated fluids. The analyses show that the fluids have remarkably uniform compositions that are similar to previously published analyses of oils (Cole and others, 1987) and gases (Laughrey and Baldasarre, 1998) in Early Silurian reservoirs elsewhere in Ohio; however, geochemical parameters in the oils and gases suggest that the fluids have experienced higher levels of thermal stress than the present-day burial conditions of the reservoir rocks. The crude oils have an unusual geochemical characteristic: they do not contain detectable levels of sterane and triterpane biomarkers. The origin of these absences is unknown.

  16. Understanding the micro structure of Berea Sandstone by the simultaneous use of micro-computed tomography (micro-CT) and focused ion beam-scanning electron microscopy (FIB-SEM). (United States)

    Bera, Bijoyendra; Mitra, Sushanta K; Vick, Douglas


    Berea sandstone is the building block for reservoirs containing precious hydrocarbon fuel. In this study, we comprehensively reveal the microstructure of Berea sandstone, which is often treated as a porous material with interconnected micro-pores of 2-5 μm. This has been possible due to the combined application of micro-computed tomography (CT) and focused ion beam (FIB)-scanning electron microscopy (SEM) on a Berea sample. While the use of micro-CT images are common for geological materials, the clubbing and comparison of tomography on Berea with state-of-the-art microstructure imaging techniques like FIB-SEM reveals some unforeseen features of Berea microstructure. In particular, for the first time FIB-SEM has been used to understand the micro-structure of reservoir rock material like Berea sandstone. By using these characterization tools, we are able to show that the micro-pores (less than 30 μm) are absent below the solid material matrix, and that it has small interconnected pores (30-40 μm) and large crater-like voids (100-250 μm) throughout the bulk material. Three-dimensional pore space reconstructions have been prepared from the CT images. Accordingly, characterization of Berea sandstone specimen is performed by calculation of pore-structure volumes and determination of porosity values.

  17. Imaging the Morrow A Sandstone Using Shear Wave VSP Data, Postle Field, Oklahoma

    Directory of Open Access Journals (Sweden)

    Naser Tamimi


    potential to enhance shear wave imaging of the thin heterogeneous Morrow A sandstone at Postle Field. The zero-offset VSP results confirm the advantages of shear wave over compressional wave in imaging the Morrow A sandstone. Also, the final shear wave VSP image shows that, applying the proposed processing flow, we are able to image the Morrow A sandstone where the thickness is as thin as 8.5 m.

  18. Evidence for subduction-related magmatism during the Cretaceous and Cenozoic in Myanmar (United States)

    Sevastjanova, Inga; Sagi, David Adam; Webb, Peter; Masterton, Sheona; Hill, Catherine; Davies, Clare


    Myanmar's complex geological history, numerous controversies around its tectonic evolution and the presence of prospective hydrocarbon basins make it a key area of interest for geologists. Understanding whether a passive or an active margin existed in the region during the Cenozoic is particularly important for the production of accurate basin models; active Cenozoic subduction would imply that hydrocarbon basins in the forearc experienced extension due to slab rollback. The geology of Myanmar was influenced by the regional tectonics associated with the Cretaceous and Cenozoic closure of the Neotethys Ocean. During this time, India travelled rapidly from Gondwana to Asia at speeds up to 20 cm/yr. To accommodate the north-eastward motion of India, the Neotethys Ocean was consumed at the subduction zone along the southern margin of Eurasia. Based on our Global Plate Model, this subduction zone can reasonably be expected to extend for the entire width of the Neotethys Ocean as far as Myanmar and Southeast Asia at their eastern extent. Moreover, a) Cretaceous volcanism onshore Myanmar, b) the middle Cenozoic arc-related extension in the Present Day eastern Andaman Sea and c) the late Cenozoic uplift of the Indo-Burman Ranges are all contemporaneous with the subduction ages predicted by the global plate motions. However, because of the geological complexity of the area, additional evidence would augment interpretations that are based on structural data. In an attempt to reduce the uncertainty in the existing interpretations, we have compiled published zircon geochronological data from detrital and igneous rocks in the region. We have used published zircon U-Pb ages and, where available, published Hf isotope data and CL images (core/rim) in order to distinguish 'juvenile' mantle-derived zircons from those of reworked crustal origin. The compilation shows that Upper Cretaceous and Cenozoic zircons, which are interpreted to have a volcanic provenance, are common across the

  19. Petrology and stratigraphy of Paleogene nonmarine sandstones, Cascade Range, Washington (United States)

    Frizzell, Virgil A.


    The Cascade Range of Washington north of 47? latitude is composed of probable Paleozoic and Mesozoic metamorphic rocks and Mesozoic and Tertiary plutonic rocks. Several Paleogene nonmarine arkosic sandstone units fringe and in part occur within the complex crystalline core. The early to middle Eocene Chuckanut Formation is present on the west side of the crystalline core in the western foothills of the Cascades. The early to middle Eocene Swauk Formation partially encircles the Mt. Stuart massif of the central Cascades. In the western foothills of the Cascades, between the main body of Chuckanut Formation near Bellingham and the main outcrop area of the Swauk Formation south of Mt. Stuart, many smaller bodies of arkosic sandstone have variously been referred to either the Swauk or Chuckanut Formations. The early Eocene Manastash Formation occurs locally in an area south of the Yakima River. The middle to late Eocene Chumstick Formation is mostly confined to the Chiwaukum graben within the crystalline core and is separated from the Swauk Formation on the southwest by the Leavenworth Fault. The Oligocene Wenatchee Formation unconformably over lies the Chumstick Formation near Wenatchee. The middle to late Eocene Roslyn Formation crops out north of the Yakima River and is underlain by the Teanaway Basalt which separates the Roslyn from the older Swauk Formation. The middle Eocene to early Oligocene Naches Formation forms a north-trending body that crosses the Yakima River and is in fault contact with both the Swauk and Manastash Formations. The middle to late Eocene Puget Group underlies the Quaternary deposits of the Puget Lowland southeast of Seattle on the western flank of the Cascades. The various formations are all composed predominantly of fine- to medium-grained sandstones with lesser amounts of interbedded shale, conglomerate and coal. Compositionally, the units are predominantly either feldspathic or litho-feldspathic subquartzose sandstones. Volcanic rocks

  20. Appalachian Basin Low-Permeability Sandstone Reservoir Characterizations

    Energy Technology Data Exchange (ETDEWEB)

    Ray Boswell; Susan Pool; Skip Pratt; David Matchen


    A preliminary assessment of Appalachian basin natural gas reservoirs designated as 'tight sands' by the Federal Energy Regulatory Commission (FERC) suggests that greater than 90% of the 'tight sand' resource occurs within two groups of genetically-related units; (1) the Lower Silurian Medina interval, and (2) the Upper Devonian-Lower Mississippian Acadian clastic wedge. These intervals were targeted for detailed study with the goal of producing geologic reservoir characterization data sets compatible with the Tight Gas Analysis System (TGAS: ICF Resources, Inc.) reservoir simulator. The first phase of the study, completed in September, 1991, addressed the Medina reservoirs. The second phase, concerned with the Acadian clastic wedge, was completed in October, 1992. This report is a combined and updated version of the reports submitted in association with those efforts. The Medina interval consists of numerous interfingering fluvial/deltaic sandstones that produce oil and natural gas along an arcuate belt that stretches from eastern Kentucky to western New York. Geophysical well logs from 433 wells were examined in order to determine the geologic characteristics of six separate reservoir-bearing intervals. The Acadian clastic wedge is a thick, highly-lenticular package of interfingering fluvial-deltaic sandstones, siltstones, and shales. Geologic analyses of more than 800 wells resulted in a geologic/engineering characterization of seven separate stratigraphic intervals. For both study areas, well log and other data were analyzed to determine regional reservoir distribution, reservoir thickness, lithology, porosity, water saturation, pressure and temperature. These data were mapped, evaluated, and compiled into various TGAS data sets that reflect estimates of original gas-in-place, remaining reserves, and 'tight' reserves. The maps and data produced represent the first basin-wide geologic characterization for either interval. This report

  1. Time-dependent compaction band formation in sandstone (United States)

    Heap, Michael J.; Brantut, Nicolas; Baud, Patrick; Meredith, Philip G.


    Compaction bands in sandstone are laterally extensive planar deformation features that are characterized by lower porosity and permeability than the surrounding host rock. As a result, this form of localization has important implications for both strain partitioning and fluid flow in the Earth's upper crust. To better understand the time dependency of compaction band growth, we performed triaxial deformation experiments on water-saturated Bleurswiller sandstone (initial porosity = 0.24) under constant stress (creep) conditions in the compactant regime. Our experiments show that inelastic strain accumulates at a constant stress in the compactant regime, manifest as compaction bands. While creep in the dilatant regime is characterized by an increase in porosity and, ultimately, an acceleration in axial strain rate to shear failure, compaction creep is characterized by a reduction in porosity and a gradual deceleration in axial strain rate. The global decrease in the rates of axial strain, acoustic emission energy, and porosity change during creep compaction is punctuated at intervals by higher rate excursions, interpreted as the formation of compaction bands. The growth rate of compaction bands formed during creep is lower as the applied differential stress, and hence, background creep strain rate, is decreased. However, the inelastic strain associated with the growth of a compaction band remains constant over strain rates spanning several orders of magnitude (from 10-8 to 10-5 s-1). We find that despite the large differences in strain rate and growth rate (from both creep and constant strain rate experiments), the characteristics (geometry and thickness) of the compaction bands remain essentially the same. Several lines of evidence, notably the similarity between the differential stress dependence of creep strain rate in the dilatant and compactant regimes, suggest that as for dilatant creep, subcritical stress corrosion cracking is the mechanism responsible for

  2. Population genetic structure of a sandstone specialist and a generalist heath species at two levels of sandstone patchiness across the Strait of Gibraltar. (United States)

    Gil-López, Manuel Jesús; Segarra-Moragues, José Gabriel; Ojeda, Fernando


    Many habitat specialist species are originally composed of small, discontinuous populations because their habitats are naturally fragmented or patchy. They may have suffered the long-term effects of natural patchiness. Mediterranean heathlands, a representative habitat in the Strait of Gibraltar region, are associated with nutrient-poor, acidic sandstone soils. Sandstone soil patches in the African side of the Strait (Tangier) are, in general, smaller and more scattered than in the European side (Algeciras). In this study, we analyze the effect of this sandstone patchiness on the population genetic diversity and structure of two Erica species from these Mediterranean heathlands that differ in their edaphic specificity, E. australis, sandstone specialist, and E. arborea, generalist. Average levels of within-population genetic diversity and gene flow between populations were significantly lower in Tangier (high sandstone patchiness) than in Algeciras (low patchiness) for the sandstone specialist, whereas no differences between both sides of the Strait were detected in the edaphic generalist. Since most endemic species in Mediterranean heathlands of the Strait of Gibraltar are sandstone specialists, these results highlight an increased vulnerability to loss of genetic diversity and local extinction of the heathland endemic flora in the Tangier side of the Strait of Gibraltar.

  3. Population genetic structure of a sandstone specialist and a generalist heath species at two levels of sandstone patchiness across the Strait of Gibraltar.

    Directory of Open Access Journals (Sweden)

    Manuel Jesús Gil-López

    Full Text Available Many habitat specialist species are originally composed of small, discontinuous populations because their habitats are naturally fragmented or patchy. They may have suffered the long-term effects of natural patchiness. Mediterranean heathlands, a representative habitat in the Strait of Gibraltar region, are associated with nutrient-poor, acidic sandstone soils. Sandstone soil patches in the African side of the Strait (Tangier are, in general, smaller and more scattered than in the European side (Algeciras. In this study, we analyze the effect of this sandstone patchiness on the population genetic diversity and structure of two Erica species from these Mediterranean heathlands that differ in their edaphic specificity, E. australis, sandstone specialist, and E. arborea, generalist. Average levels of within-population genetic diversity and gene flow between populations were significantly lower in Tangier (high sandstone patchiness than in Algeciras (low patchiness for the sandstone specialist, whereas no differences between both sides of the Strait were detected in the edaphic generalist. Since most endemic species in Mediterranean heathlands of the Strait of Gibraltar are sandstone specialists, these results highlight an increased vulnerability to loss of genetic diversity and local extinction of the heathland endemic flora in the Tangier side of the Strait of Gibraltar.

  4. Water Vapor Diffusion and Adsorption of Sandstones: Influence of Rock Texture and Composition

    Directory of Open Access Journals (Sweden)

    Martin Keppert


    Full Text Available The term sandstone is used for wide range of rocks containing quartz clasts which can be cemented by secondary precipitated quartz or calcite; moreover the space between clasts can be filled by matrix. These facts result in existence of numerous rocks having highly various properties. Sandstones have been used as construction materials due to their good accessibility and workability. Since most of sandstones are porous, water vapor can penetrate through sandstone constructions. The rate of water vapor diffusion, as well as the vapor sorption isotherm, was determined for range of sandstone types. The diffusion resistance factor was found to be dependent on the total porosity of sandstone but the sorption behavior was strongly influenced by nature of the particular sandstone; the specific surface area of stone and presence of clay matrix are determining its sorption isotherm. The published data enable estimating (i diffusion resistance factor of a sandstone via knowledge of its total porosity and (ii the sorption isotherm via knowledge of the stone’s nature and specific surface area. This approach can significantly reduce the time necessary to acquire vapor-related properties of a sandstone.

  5. Mechanical properties and failure characteristics of fractured sandstone with grouting and anchorage

    Institute of Scientific and Technical Information of China (English)

    Zong Yijiang; Han Lijun; Qu Tao; Yang Shengqi


    Based on uniaxial compression experimental results on fractured sandstone with grouting and anchorage, we studied the strength and deformation properties, the failure model, crack formation and evolution laws of fractured sandstone under different conditions of anchorage. The experimental results show that the strength and elastic modulus of fractured sandstone with different fracture angles are sig-nificantly lower than those of intact sandstone. Compared with the fractured samples without anchorage, the peak strength, residual strength, peak and ultimate axial strain of fractured sandstone under different anchorage increase by 64.5-320.0%, 62.8-493.0%, and 31.6-181.4%, respectively. The number of bolts and degree of pre-stress has certain effects on the peak strength and failure model of fractured sandstone. The peak strength of fractured sandstone under different anchorage increases to some extent, and the failure model of fractured sandstone also transforms from tensile failure to tensile-shear mixed failure with the number of bolts. The pre-stress can restrain the formation and evolution process of tensile cracks, delay the failure process of fractured sandstone under anchorage and impel the transformation of failure model from brittle failure to plastic failure.

  6. Magnetic Titanohematite Minerals in Uranium-Bearing Sandstones (United States)

    Reynolds, Richard L.


    Detrital grains of the rhombohedral ilmenite (FeT1O3)--hematite (Fe2O3) solid solution series (titanohematites) have been identified by thermomagnetic, reflection microscopic, and X-ray diffraction analysis in six uranium-bearing sandstones in the western United States. Many of the titanohematites are ferrimagnetic and have Curie temperatures ranging from about 70 Deg C to 220 Deg C. Magnetic titanohematite is commonly more abundant than magnetite in many samples and, therefore, should be considered as a major source of the permanent magnetization in these units.

  7. Diagenesis, provenance and depositional environments of the Bunter Sandstone Formation

    DEFF Research Database (Denmark)

    Olivarius, Mette; Weibel, Rikke; Friis, Henrik

    The Bunter Sandstone Formation in the northern North German Basin has large geothermal potential with high porosity and permeability (generally >15% and >100 mD, respectively) and with pore fluid temperatures that are adequate for geothermal energy production (c. 55–60˚C). A combined investigation...... of diagenesis, provenance and depositional environments is used to identify the reservoir rocks that possess the best quality. This is accomplished by integrating various methods including: seismic reflection data, sedimentological description of cores, mineral quantification by point counting, measurement...

  8. Reservoir characterization of Pennsylvanian sandstone reservoirs. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Kelkar, M.


    This final report summarizes the progress during the three years of a project on Reservoir Characterization of Pennsylvanian Sandstone Reservoirs. The report is divided into three sections: (i) reservoir description; (ii) scale-up procedures; (iii) outcrop investigation. The first section describes the methods by which a reservoir can be described in three dimensions. The next step in reservoir description is to scale up reservoir properties for flow simulation. The second section addresses the issue of scale-up of reservoir properties once the spatial descriptions of properties are created. The last section describes the investigation of an outcrop.

  9. Simulation of channel sandstone architecture in an incised valley

    Energy Technology Data Exchange (ETDEWEB)

    Frykman, P.; Johannessen, P.; Andsbjerg, J.


    The present report describes a geostatistical modelling study that is aimed at reflecting the architecture of the channel sandstones in an incised valley fill. The example used for this study is a part of the Middle Jurassic sandy succession of the Bryne Formation in the Danish central Graben. The succession consists mainly of fluvial sediments in the lower part, overlain by tidal influenced sediments, which again is overlain by shallow marine sediments. The modelling study has been performed on a sequence of incised valley sediments in the upper part of the Bryne Formation overlying fluvial sediments. (au) EFP-96. 19 refs.

  10. Initiation of acoustic emission in fluid-saturated sandstone samples (United States)

    Lapshin, V. B.; Patonin, A. V.; Ponomarev, A. V.; Potanina, M. G.; Smirnov, V. B.; Stroganova, S. M.


    A rock behavior experiment with uniaxial compression revealed the effect of acoustic activity in loaded fluid-saturated Berea sandstone samples in response to an electric current. It is established that it is substantially intensified in periods of the current impact and decreases after its cut-off. The current impact also results in a growth of radial deformation indicating an increase in the sample volume. The effect of acoustic activation increases in response to increased heat emitted by the electric current during its flow through the sample, which allows the discovered effect to be explained by initiation of its destruction due to thermal expansion of the fluid in rock interstices and fissures.

  11. Geological Evidence That Resolves the Baja-BC Controversy: Detrital Zircons Indicate That Vancouver Island Was Adjacent to Southern California in the Late Cretaceous (United States)

    Guest, B.; Matthews, W.; Coutts, D. S.; Bain, H.; Hubbard, S. M.


    The Baja-BC hypothesis is at the center of a great earth sciences controversy. It stems from paleomagnetic observations that require large-scale displacements of continental crust from low latitudes (Baja, California) to moderate latitudes (British Columbia). Many geologists dispute the scale of the displacements due to a lack of corroborating geological evidence. We provide a robust, geological dataset that confirms the paleomagnetic observations. Detrital zircons from Cretaceous to Paleocene sandstone of the Nanaimo Group, which crops out in western Vancouver Island and the Gulf Islands of southwest British Columbia, are analyzed. The data show a clear transition from local 300 Ma grains in the Maastrichtian-Paleogene. An identical pattern is observed in detrital zircon datasets from southern California forearc basin deposits, and schists interpreted as the subducted remnants of forearc deposits. With a high-n dataset (n=3041) we are able to rule out possible >300 Ma source regions in Canada and the northern United States, and uniquely tie Nanaimo Group rocks to the Mojave-Sonora region of SW United States. This implies that at the end of the Cretaceous, Vancouver Island and western mainland BC were adjacent to southern California and northwestern Mexico, requiring 1900 km of displacement during the latest Cretaceous and Paleocene, consistent with paleomagnetic results. An implication of this result is that the western Coast Batholith of southwest BC was positioned between the northern Peninsular Ranges and southern Sierra Nevada batholiths in the late Cretaceous, and likely represents a displaced segment of a once continuous Cordilleran arc batholith. These results have broad implications for our understanding of episodic arc magmatism in the Cordillera, the tectonic evolution of western North America, Laramide orogenesis, the development and extent of the Nevadaplano, and the onset of Basin and Range extension.

  12. Compaction history of Upper Cretaceous shale (Al-Khod Formation) and its relationship to plate margin tectonics, Arabian Plate, Sultanate of Oman (United States)

    AL-Sarmi, Musaab; Mattern, Frank; Scharf, Andreas; Pracejus, Bernhard; Al-Mamari, Amira; Al-Hinaai, Al-Shima


    Conglomerates of the late Cretaceous Al-Khod Formation have been intruded by older shale of the same formation along faults, which were opened/widened by extension, thus, resulting in shale dike formation. Following intrusion the shale was behaving plastically as its fissility follows the contact contours of the conglomeratic host rock and as stoped sandstone blocks are floating within the shale. Vertical calcite veins were ptygmatically folded with subhorizontal fold axial planes. All these aspects show that the shale contained a high water content in the beginning. The ptygmatically folded calcite veins display vertical shortening amounts of 40 % corresponding to 35 % to 45 % of water loss during compaction. Incalculable numbers of calcite veins of different orientations and thicknesses within the conglomerate along the shale contact indicate that the fluid was expelled from the shale into the conglomerate host rock under high pressure (overpressure?). Shale dyke formation took place after the late Cretaceous obduction of the Semail Ophiolite, before the deposition of early Tertiary carbonate rocks, and during the latest Cretaceous doming of the Saih Hatat area which was caused by deformation and slab breakoff, likely associated with gravitational collapse and elastic rebound. Shale intrusion was followed by deposition of 100 to 200 m thick sediments of the upper part of Al-Khod Formation, leading to compaction and water loss. The shale retained much of its water during the uppermost Cretaceous-late Paleocene stratigraphic hiatus as this interval is marked by erosion and a reduction of overburden, which was probably due to the elastic rebound. Folding of calcite veins together with a high amount of water loss was a consequence of compaction caused by the overburden of 1000 m thick shallow marine limestones which were deposited from the Eocene to Oligocene.

  13. Preliminary stratigraphy and facies analysis of the Upper Cretaceous Kaguyak Formation, including a brief summary of newly discovered oil stain, upper Alaska Peninsula (United States)

    Wartes, Marwan A.; Decker, Paul L.; Stanley, Richard G.; Herriott, Trystan M.; Helmold, Kenneth P.; Gillis, Robert J.


    The Alaska Division of Geological and Geophysical Surveys has an ongoing program aimed at evaluating the Mesozoic forearc stratigraphy, structure, and petroleum systems of lower Cook Inlet. Most of our field studies have focused on the Jurassic component of the petroleum system (this report). However, in late July and early August of 2012, we initiated a study of the stratigraphy and reservoir potential of the Upper Cretaceous Kaguyak Formation. The Kaguyak Formation is locally well exposed on the upper Alaska Peninsula (fig. 25) and was named by Keller and Reiser (1959) for a sequence of interbedded siltstone and sandstone of upper Campanian to Maastrichtian age that they estimated to be 1,450 m thick.Subsequent work by Detterman and Miller (1985) examined 900 m of section and interpreted the unit as the record of a prograding submarine fan.This interpretation of deep-water deposition contrasts with other Upper Cretaceous rocks exposed along the Alaska Peninsula and lower Cook Inlet that are generally described as nonmarine to shallow marine (Detterman and others, 1996; LePain and others, 2012).Based on foraminifera and palynomorphs from the COST No. 1 well, Magoon (1986) concluded that the Upper Cretaceous rocks were deposited in a variety of water depths and environments ranging from upper bathyal to nonmarine. During our recent fieldwork west and south of Fourpeaked Mountain, we similarly encountered markedly varying lithofacies in the Kaguyak Formation (fig. 25), and we also found oil-stained rocks that are consistent with the existence of an active petroleum system in Upper Cretaceous rocks on the upper Alaska Peninsula and in lower Cook Inlet. These field observations are summarized below.

  14. Scientific Drilling of the Terrestrial Cretaceous Songliao Basin

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    Terrestrial Scientific Drilling of the Cretaceous Songliao Basin Science Team


    Full Text Available Investigations of critical climate changes during the Cretaceous have the potential to enhance our understanding of modern global warming because the extreme variances are the best-known and most recent example of a greenhouse Earth (Bice et al., 2006. Marine Cretaceous climate archives are relatively well explored by scientific ocean drilling programs such as the Integrated Ocean Drilling Program (IODP and its predecessors. However, Cretaceous terrestrial climate records are at best fragmentary (Heimhofer et al., 2005. The long-lived Cretaceous Songliao Basin of NE China is an excellent candidate to fill this gap and provide important ocean-continent linkages in relation to environmental change (Fig. 1. This basin, located within one of the largest Cretaceous landmasses (Scotese, 1988, acted for about 100 million years as an intra-continental sediment trap; the present-day area of the basin is about 260,000 km2. It provides an almost complete terrestrial sedimentary recordfrom the Upper Jurassic to the Paleocene (Chen and Chang, 1994. Large-scale geological and geophysical investigations of lacustrine sediments and basin structures demonstrate that a rich archive of Cretaceous paleoclimate proxies exists. For example, the basin includes the Jehol Biota, a terrestrial response to the Cretaceous oceanic anoxic events (OAEs, and a potential K/T boundary (Qiang et al., 1998. An ongoing drilling program is supported by the Ministry of Science and Technology of China and by the Daqing Oilfield. It allowed for recovering of nearly complete cores from Upper Albian to the Uppermost Cretaceous in two boreholes (SK-I, SK II; commenced in 2006, Fig. 1. However, the older Cretaceous sedimentary record of Songliao Basin has not yet been cored. For that reason, a scientific drilling program has been proposed to the International Continental Scientific Drilling Program (ICDP to sample the deeper sedimentaryrecord of the Songliao Basin through a new drill hole

  15. 鄂尔多斯盆地富县—正宁地区延长组油气成藏期次%Classification of hydrocarbon accumulation phases of the Yanchang Formation in the Fuxian-Zhengning area, Ordos Basin

    Institute of Scientific and Technical Information of China (English)

    梁宇; 任战利; 史政; 赵筱燕; 于强; 吴晓青


    鄂尔多斯盆地富县—正宁地区延长组砂岩储层主要成岩作用有压实作用、胶结作用、溶蚀作用和裂隙作用,成岩自生矿物以绿泥石、自生石英和方解石为主.根据油气包裹体寄主成岩矿物的形成时间序列,识别出两期油气包裹体:第1期油气包裹体主要分布在石英、长石粒内愈合的、未切穿次生加大边的微裂隙及石英次生加大边内侧;第2期油气包裹体分布在晚期微裂隙和晚期亮晶方解石胶结物中.油气包裹体均一温度分布呈双峰型:早期峰值温度为110~120℃;晚期峰值温度为140~150℃.对油气包裹体均一温度、盐度、密度分析表明,研究区延长组油气为“一期两幕”成藏,且具有“边致密,边成藏”的特点.结合研究区延长组热演化史及储层伊利石K-Ar同位素定年结果研究表明,研究区主要油气成藏期为早白垩世(距今95~120Ma).%The main diagenesis of the Yanchang Formation sandstone reservoirs in the Fuxian-Zhengning area, Ordos Basin, includes compaction, cementation, corrosion and fracturation, and diagenetic authigenic minerals in these reservoirs are dominated by chlorite, authigenetic quartz and calcite. Two phases of hydrocarbon inclusions have been identified according to the time sequence of the formation of host diagenetic minerals, the earlier one composed of mostly brine inclusions that contain gaseous or liquid hydrocarbons either occurs along healed microfractures wrapped up by secondary growth edges of quartz or feldspar, or is trapped at the bottom of secondary growth edges of quartz or feldspar, while the later one mostly consisting of gas-liquid or liquid hydrocarbon inclusions occurs along the late-formed microfractures or in sparry calcite cements. Homogenization temperatures measured from brine inclusions associated with hydrocarbon ones show a bimodal distribution in the ranges with 110~120'C and 140~150'C as peak temperatures

  16. Stratigraphy and structural setting of Upper Cretaceous Frontier Formation, western Centennial Mountains, southwestern Montana and southeastern Idaho (United States)

    Dyman, T.S.; Tysdal, R.G.; Perry, W.J.; Nichols, D.J.; Obradovich, J.D.


    Stratigraphic, sedimentologic, and palynologic data were used to correlate the Frontier Formation of the western Centennial Mountains with time-equivalent rocks in the Lima Peaks area and other nearby areas in southwestern Montana. The stratigraphic interval studied is in the middle and upper parts (but not uppermost) of the formation based on a comparison of sandstone petrography, palynologic age data, and our interpretation of the structure using a seismic line along the frontal zone of the Centennial Mountains and the adjacent Centennial Valley. The Frontier Formation is comprised of sandstone, siltstone, mudstone, limestone, and silty shale in fluvial and coastal depositional settings. A distinctive characteristic of these strata in the western Centennial Mountains is the absence of conglomerate and conglomeratic sandstone beds. Absence of conglomerate beds may be due to lateral facies changes associated with fluvial systems, a distal fining of grain size, and the absence of both uppermost and lower Frontier rocks in the study area. Palynostratigraphic data indicate a Coniacian age for the Frontier Formation in the western Centennial Mountains. These data are supported by a geochronologic age from the middle part of the Frontier at Lima Peaks indicating a possible late Coniacian-early Santonian age (86.25 ?? 0.38 Ma) for the middle Frontier there. The Frontier Formation in the western Centennial Mountains is comparable in age and thickness to part of the Frontier at Lima Peaks. These rocks represent one of the thickest known sequences of Frontier strata in the Rocky Mountain region. Deposition was from about 95 to 86 Ma (middle Cenomanian to at least early Santonian), during which time, shoreface sandstone of the Telegraph Creek Formation and marine shale of the Cody Shale were deposited to the east in the area now occupied by the Madison Range in southwestern Montana. Frontier strata in the western Centennial Mountains are structurally isolated from other

  17. Imaging cross fault multiphase flow using time resolved high pressure-temperature synchrotron fluid tomography: implications for the geological storage of carbon dioxide within sandstone saline aquifers (United States)

    Seers, Thomas; Andrew, Matthew; Bijeljic, Branko; Blunt, Martin; Dobson, Kate; Hodgetts, David; Lee, Peter; Menke, Hannah; Singh, Kamaljit; Parsons, Aaron


    Applied shear stresses within high porosity granular rocks result in characteristic deformation responses (rigid grain reorganisation, dilation, isovolumetric strain, grain fracturing and/or crushing) emanating from elevated stress concentrations at grain contacts. The strain localisation features produced by these processes are generically termed as microfaults (also shear bands), which occur as narrow tabular regions of disaggregated, rotated and/or crushed grains. Because the textural priors that favour microfault formation make their host rocks (esp. porous sandstones) conducive to the storage of geo-fluids, such structures are often abundant features within hydrocarbon reservoirs, aquifers and potential sites of CO2 storage (i.e. sandstone saline aquifers). The porosity collapse which accompanies microfault formation typically results in localised permeability reduction, often encompassing several orders of magnitude. Given that permeability is the key physical parameter that governs fluid circulation in the upper crust, this petrophysical degradation implicates microfaults as being flow impeding structures which may act as major baffles and/or barriers to fluid flow within the subsurface. Such features therefore have the potential to negatively impact upon hydrocarbon production or CO2 injection, making their petrophysical characterisation of considerable interest. Despite their significance, little is known about the pore-scale processes involved in fluid trapping and transfer within microfaults, particularly in the presence of multiphase flow analogous to oil accumulation, production and CO2 injection. With respect to the geological storage of CO2 within sandstone saline aquifers it has been proposed that even fault rocks with relatively low phyllosilicate content or minimal quartz cementation may act as major baffles or barriers to migrating CO2 plume. Alternatively, as ubiquitous intra-reservoir heterogeneities, micro-faults also have the potential to

  18. Measuring the zeta potential. The relationships with sandstone fineness

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    de Luxán, M. P.


    Full Text Available The application of the zeta potential technique in the area of construction materials and Portland cement is quite recent. The initial research work involved the study of cement suspensions or suspensions of one of the components of cement, such as alite, tricalcium alumínate, in the presence of additives and, more specifically, superplasticizers. The studies of this sort were extended with the mixing of active additions into cement (fly ashes, etc.. The present study discusses the application of siliceous materials (sandstone as a basis of the research into the behaviour of sandstone mortars containing repair products.

    La aplicación de la técnica del potencial zeta en el campo de los materiales de construcción y del cemento portland es muy reciente. Las primeras investigaciones se refieren al estudio de suspensiones de cemento o de alguno de sus compuestos que lo forman como alita, aluminato tricálcico, en presencia de aditivos y, más concretamente, de superfluidificantes. Con la incorporación de adiciones activas al cemento (cenizas volantes,... se amplían los estudios de este tipo de cementos. En este trabajo se considera la aplicación a los materiales silíceos (arenisca como base para la investigación del comportamiento de los morteros de arenisca conteniendo productos de reparación.

  19. The Creep Properties of Fine Sandstone under Uniaxial Tensile Stress

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    Jiang Haifei


    Full Text Available A graduated uniaxial direct tensile creep test for fine sandstone is conducted by adopting a custom-designed direct tensile test device for rock. The experiment shows that the tensile creep of fine sandstone has similar creep curve patterns to those of compression creep, while the ratios of the creep strain to the total strain obtained in the tensile tests are substantially higher than those obtained for similar compression tests, which indicates that the creep ability of rock in the tensile process is higher than that in the uniaxial compression process. Based on the elastic modulus in the approximately linear portion of the obtained isochronous stress-strain curves of the tensile creep, the time dependence of the elasticity modulus for the Kelvin model is evaluated, and a revised generalized Kelvin model is obtained by substitution into the generalized Kelvin model. A new viscousplastic model is proposed to describe the accelerated creep properties, and this model is combined in series with the revised generalized Kelvin model to form a new nonlinear viscoelastic-plastic creep model that can describe the properties of attenuation creep, steady creep, and accelerated creep. Comparison of the test and theoretical curves demonstrates that they are nearly identical, which verifies the performance of the model.

  20. Microstructural changes of sandstone specimens during CO2 injection (United States)

    Park, J. H.; Son, J.; Oh, M.; Park, H. D.


    Carbon dioxide capture and storage (CCS) is a technology to isolate CO2 from atmosphere, by capturing it from sources, transporting it to injection area, and injecting it into suitable geological formation, ocean, or mineral carbonation plant. Geological storage of carbon dioxide is the most effective and economical method, and until now a lot of demonstration projects were carried out successfully such as Sleipner, Weyburn, and In Salah. In Republic of Korea, small-scale CO2 injection demonstration project is now under investigation in offshore Pohang Basin with sandstone reservoir and the mudstone caprock. When CO2 is injected in target site, the rock around injection well can be deteriorated because of extreme change of temperature and pressure. In this study supercritical CO2 was injected in sandstone specimen and the initiation and propagation of fracture inside the specimens were observed using X-ray computed tomography (CT). X-ray CT method is a computer technology to observe inner density of target object in three dimensional image. Because of its non-destructivity and high resolution, it is suitable for consistent observation of the same specimen. Porosity and permeability of the specimens were measured using X-ray CT images and both of them were increased after injection. P- and S-wave velocity were also measured to assess the change of mechanical property and both of them were decreased after injection because of growth of inner fractures. The data from this research can be used as input data of CCS site.

  1. Water coning mechanism in Tarim fractured sandstone gas reservoirs

    Institute of Scientific and Technical Information of China (English)

    沈伟军; 刘晓华; 李熙喆; 陆家亮


    The problem of water coning into the Tarim fractured sandstone gas reservoirs becomes one of the major concerns in terms of productivity, increased operating costs and environmental effects. Water coning is a phenomenon caused by the imbalance between gravity and viscous forces around the completion interval. There are several controllable and uncontrollable parameters influencing this problem. In order to simulate the key parameters affecting the water coning phenomenon, a model was developed to represent a single well with an underlying aquifer using the fractured sandstone gas reservoir data of the A-Well in Dina gas fields. The parametric study was performed by varying six properties individually over a representative range. The results show that matrix permeability, well penetration (especially fracture permeability), vertical-to-horizontal permeability ratio, aquifer size and gas production rate have considerable effect on water coning in the fractured gas reservoirs. Thus, investigation of the effective parameters is necessary to understand the mechanism of water coning phenomenon. Simulation of the problem helps to optimize the conditions in which the breakthrough of water coning is delayed.

  2. Dispersion analysis of velocity and attenuation in Berea sandstone (United States)

    Winkler, Kenneth W.


    Ultrasonic velocity and attenuation measurements were made on dry, brine- and oil-saturated Berea sandstone and fused glass beads. The results for fused glass beads are consistent with the predictions of Biot theory. They indicate that as predicted, the Biot absorption/dispersion mechanism shifts to higher frequencies as the fluid viscosity increases. Similar data for Berea sandstone are not consistent with Biot theory, since observed velocities are generally higher than predicted. Using the Biot theory, we calculate low- and high-frequency velocities for the liquid-saturated samples. "Biot dispersion" is then defined as the percent difference between the low- and high-frequency limits. "Apparent dispersion" is defined as the percent difference between the measured ultrasonic velocity and the low-frequency Biot limit. Comparison of these two measures of dispersion gives insight into the presence of a non-Biot absorption/dispersion mechanism. Whenever the apparent dispersion is larger than the Biot dispersion, the extra dispersion is interpreted as being caused by a local flow relaxation. To be consistent with attenuation data, this relaxation must be distributed over at least five to six decades in frequency.

  3. Selected trace and minor elements in sandstones from Paraguay

    Energy Technology Data Exchange (ETDEWEB)

    Facetti-Masulli, J.F.; Gonzalez, E. [Hydroconsult SRL, Asuncion (Paraguay); Kump, P. [J. Stefan Inst., Ljubljana (Slovenia)


    Selected trace and minor elements analyzed by XRF in sandstone samples were Rb-Sr-Zr-Nb-Ba-La-Ce-Nd as well as Ti-Mn-Fe with which they are often correlated. Refractory elements like REE are considered useful indicators of geochemical processes and, in this case, of provenance. Usually they maintain their original relationships and are transferred almost directly into sediments. The values here found, absolute and normalized, show correlations among the samples, allowing the establishment of their origin. Most of them in the spidergram patterns display positive spikes of Zr, and negative anomalies at Nb, Sr, Ti: differences in their height/depth could be in relation with the different Series or Formations. Strikingly, spidergrams of samples collected from the Patino Formation show marked negative anomalies interalia of Ba, as well as positive spikes of Nb and Zr, very similar to those found in magmatic specimens from Misiones, Carapegua-Acahay and Alto Paraguay Province and quite different from the other analyzed samples. In addition a remarkable presence of Precambrian signatures were found in the analyzed sandstones from the Paleozoic. (orig.)

  4. Acoustic Emission Parameters of Three Gorges Sandstone during Shear Failure

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    Xu Jiang


    Full Text Available In this paper, an experimental investigation of sandstone samples from the Three Gorges during shear failure was conducted using acoustic emission (AE and direct shear tests. The AE count rate, cumulative AE count, AE energy, and amplitude of the sandstone samples were determined. Then, the relationships among the AE signals and shearing behaviors of the samples were analyzed in order to detect micro-crack initiation and propagation and reflect shear failure. The results indicated that both the shear strength and displacement exhibited a logarithmic relationship with the displacement rate at peak levels of stress. In addition, the various characteristics of the AE signals were apparent in various situations. The AE signals corresponded with the shear stress under different displacement rates. As the displacement rate increased, the amount of accumulative damage to each specimen decreased, while the AE energy peaked earlier and more significantly. The cumulative AE count primarily increased during the post-peak period. Furthermore, the AE count rate and amplitude exhibited two peaks during the peak shear stress period due to crack coalescence and rock bridge breakage. These isolated cracks later formed larger fractures and eventually caused ruptures.

  5. Core-log integration for a Saudi Arabian sandstone reservoir

    Energy Technology Data Exchange (ETDEWEB)

    Saha, S.; Al-Kaabi, A.U.; Amabeoku, M.O.; Al-Fossail, K.


    For a detailed characterization of a reservoir, core-log integration is essential. In this paper, data integration from logs and cores of a Saudi Arabian sandstone reservoir is discussed with particular attention to effects of clay on resistivity logs and water saturation. There are four sources of data, namely, core resistivity measurement, clay study from cores (XRD, CEC), spectral core gamma ray, and well logs. In order to generate continuous cation exchange capacity (CEC) with depth, spectral gamma ray measurements (both from core and downhole log) and CEC from cores and correlated. Q{sub v} (CEC per unit pore volume) values are calculated utilizing only well logs by applying Waxman-Smits equation in water bearing zone. Log derived Q{sub v} values from water zone were then correlated with porosity to generate Q{sub v} values in the oil column and compared with core derived Z{sub v}. Finally, data from well logs (porosity, resistivity and Q{sub v}) and cores (resistivity parameters m, n, and Q{sub v}) were integrated for more accurate water saturation calculation. The core-log correlation can be applied to other wells avoiding expensive core analysis, and the technique developed in this project can be used in other sandstone reservoirs.

  6. Chapter 2: 2003 Geologic Assessment of Undiscovered Conventional Oil and Gas Resources in the Upper Cretaceous Navarro and Taylor Groups, Western Gulf Province, Texas (United States)

    Condon, S.M.; Dyman, T.S.


    The Upper Cretaceous Navarro and Taylor Groups in the western part of the Western Gulf Province were assessed for undiscovered oil and gas resources in 2003. The area is part of the Smackover-Austin-Eagle Ford Composite Total Petroleum System. The rocks consist of, from youngest to oldest, the Escondido and Olmos Formations of the Navarro Group and the San Miguel Formation and the Anacacho Limestone of the Taylor Group (as well as the undivided Navarro Group and Taylor Group). Some units of the underlying Austin Group, including the 'Dale Limestone' (a term of local usage that describes a subsurface unit), were also part of the assessment in some areas. Within the total petroleum system, the primary source rocks comprise laminated carbonate mudstones and marine shales of the Upper Jurassic Smackover Formation, mixed carbonate and bioclastic deposits of the Upper Cretaceous Eagle Ford Group, and shelf carbonates of the Upper Cretaceous Austin Group. Possible secondary source rocks comprise the Upper Jurassic Bossier Shale and overlying shales within the Upper Jurassic to Lower Cretaceous Cotton Valley Group, Lower Cretaceous marine rocks, and the Upper Cretaceous Taylor Group. Oil and gas were generated in the total petroleum system at different times because of variations in depth of burial, geothermal gradient, lithology, and organic-matter composition. A burial-history reconstruction, based on data from one well in the eastern part of the study area (Jasper County, Tex.), indicated that (1) the Smackover generated oil from about 117 to 103 million years ago (Ma) and generated gas from about 52 to 41 Ma and (2) the Austin and Eagle Ford Groups generated oil from about 42 to 28 Ma and generated gas from about 14 Ma to the present. From the source rocks, oil and gas migrated upsection and updip along a pervasive system of faults and fractures as well as along bedding planes and within sandstone units. Types of traps include stratigraphic pinchouts, folds, faulted

  7. Origin of the Tertiary reservoired hydrocarbons along the central Texas and Louisiana Gulf Coast rim

    Energy Technology Data Exchange (ETDEWEB)

    Cole, G.A.; Sassen, R. (BP Exploration, Inc., Houston, TX (USA)); Chinn, E.W. (Louisiana State Univ., Baton Rouge (USA)); Piggott, N.; Gibbons, M.J.


    Tertiary reservoired hydrocarbons along the central Texas and Louisiana Gulf Coast rim were most likely derived from Paleocene/Eocene Wilcox Group and Sparta Formation marine shales. Sixteen total soluble extracts and >200 oil samples were analyzed using carbon isotopic techniques ({delta}{sup 13}C) and gas chromatography-mass spectometry (GC-MS). Results demonstrated that interpretations must use all types of data because Cretaceous derived and Tertiary derived oils overlap in southern Louisiana. When isotopic, sterane, hopane, and light hydrocarbon data are combined separation of classes become possible. Cretaceous oils and extracts have a full range of extended hopanes, a characteristic peak eluting immediately after C{sub 30} hopane and no oleanane. Paleogene oils and extracts have oleanane and a restricted range of extended hopanes. Regional trends indicate that eastern Louisiana oils were derived from the Sparta or a Sparta/Wilcox mix, the Mississippi delta oils from a Cretaceous clastic source, and western Louisiana and Texas oils from the Wilcox source. Regional variations in GOR/CGR are a function of timing and mechanism of migration.

  8. Characterizing gas shaly sandstone reservoirs using the magnetic resonance technology in the Anaco area, East Venezuela

    Energy Technology Data Exchange (ETDEWEB)

    Fam, Maged; August, Howard [Halliburton, Houston, TX (United States); Zambrano, Carlos; Rivero, Fidel [PDVSA Gas (Venezuela)


    With demand for natural gas on the rise every day, accounting for and booking every cubic foot of gas is becoming very important to operators exploiting natural gas reservoirs. The initial estimates of gas reserves are usually established through the use of petrophysical parameters normally based on wireline and/or LWD logs. Conventional logs, such as gamma ray, density, neutron, resistivity and sonic, are traditionally used to calculate these parameters. Sometimes, however, the use of such conventional logs may not be enough to provide a high degree of accuracy in determining these petrophysical parameters, which are critical to reserve estimates. Insufficient accuracy can be due to high complexities in the rock properties and/or a formation fluid distribution within the reservoir layers that is very difficult to characterize with conventional logs alone. The high degree of heterogeneity in the shaly sandstone rock properties of the Anaco area, East Venezuela, can be characterized by clean, high porosity, high permeability sands to very shaly, highly laminated, and low porosity rock. This wide variation in the reservoir properties may pose difficulties in identifying gas bearing zones which may affect the final gas reserves estimates in the area. The application of the magnetic resonance imaging (MRI) logging technology in the area, combined with the application of its latest acquisition and interpretation methods, has proven to be very adequate in detecting and quantifying gas zones as well as providing more realistic petrophysical parameters for better reserve estimates. This article demonstrates the effectiveness of applying the MRI logging technology to obtain improved petrophysical parameters that will help better characterize the shaly-sands of Anaco area gas reservoirs. This article also demonstrates the value of MRI in determining fluid types, including distinguishing between bound water and free water, as well as differentiating between gas and liquid

  9. Geochemical modeling of diagenetic reactions in Snorre Field reservoir sandstones: a comparative study of computer codes

    Directory of Open Access Journals (Sweden)

    Marcos Antonio Klunk

    Full Text Available ABSTRACTDiagenetic reactions, characterized by the dissolution and precipitation of minerals at low temperatures, control the quality of sedimentary rocks as hydrocarbon reservoirs. Geochemical modeling, a tool used to understand diagenetic processes, is performed through computer codes based on thermodynamic and kinetic parameters. In a comparative study, we reproduced the diagenetic reactions observed in Snorre Field reservoir sandstones, Norwegian North Sea. These reactions had been previously modeled in the literature using DISSOL-THERMAL code. In this study, we modeled the diagenetic reactions in the reservoirs using Geochemist's Workbench (GWB and TOUGHREACT software, based on a convective-diffusive-reactive model and on the thermodynamic and kinetic parameters compiled for each reaction. TOUGHREACT and DISSOL-THERMAL modeling showed dissolution of quartz, K-feldspar and plagioclase in a similar temperature range from 25 to 80°C. In contrast, GWB modeling showed dissolution of albite, plagioclase and illite, as well as precipitation of quartz, K-feldspar and kaolinite in the same temperature range. The modeling generated by the different software for temperatures of 100, 120 and 140°C showed similarly the dissolution of quartz, K-feldspar, plagioclase and kaolinite, but differed in the precipitation of albite and illite. At temperatures of 150 and 160°C, GWB and TOUGHREACT produced different results from the DISSOL-THERMAL, except for the dissolution of quartz, plagioclase and kaolinite. The comparative study allows choosing the numerical modeling software whose results are closer to the diagenetic reactions observed in the petrographic analysis of the modeled reservoirs.

  10. Effects of hydrocarbon generation on fluid flow in the Ordos Basin and its relationship to uranium mineralization

    Directory of Open Access Journals (Sweden)

    Chunji Xue


    Full Text Available The Ordos Basin of North China is not only an important uranium mineralization province, but also a major producer of oil, gas and coal in China. The genetic relationship between uranium mineralization and hydrocarbons has been recognized by a number of previous studies, but it has not been well understood in terms of the hydrodynamics of basin fluid flow. We have demonstrated in a previous study that the preferential localization of Cretaceous uranium mineralization in the upper part of the Ordos Jurassic section may have been related to the interface between an upward flowing, reducing fluid and a downward flowing, oxidizing fluid. This interface may have been controlled by the interplay between fluid overpressure related to disequilibrium sediment compaction and which drove the upward flow, and topographic relief, which drove the downward flow. In this study, we carried out numerical modeling for the contribution of oil and gas generation to the development of fluid overpressure, in addition to sediment compaction and heating. Our results indicate that when hydrocarbon generation is taken into account, fluid overpressure during the Cretaceous was more than doubled in comparison with the simulation when hydrocarbon generation was not considered. Furthermore, fluid overpressure dissipation at the end of sedimentation slowed down relative to the no-hydrocarbon generation case. These results suggest that hydrocarbon generation may have played an important role in uranium mineralization, not only in providing reducing agents required for the mineralization, but also in contributing to the driving force to maintain the upward flow.

  11. Evolution and hydrocarbon potential of offshore Pinar Del Rio area, Southern Gulf of Mexico

    Energy Technology Data Exchange (ETDEWEB)

    Tenreyro-Perez, R.; Lopez-Rivera, J.G.; Fernandez-Carmona, J.; Lopez-Quintero, J.O.


    The evolution of Southeast Gulf of Mexico comprises three main periods: pre-orogenic, syn-orogenic and post-orogenic. During pre-orogenic time, from Lower Jurassic to Campanian, the stages are the rift of Pangaea and the thermal subsidence (or drift). In drift stage two domains interacted in the space; the carbonate platforms (Bahamas, Yucatan, Organos and others), and the deepwater basins. These fluctuations were dictated by the differential subsidence and horizontal displacements of basement blocks as well as by the eustatic movements of the ocean. The Organos platform, for example, was entirely drowned since Upper Jurassic and the sedimentation continued in deepwater environment. The collision between Great Antilles Volcanic Arc and the continental margins since Upper Cretaceous modeled the Cuban orogen. Here, the southern facies thrusted over the northern section with simultaneous strike-slip movements. The interaction suddenly ceased in Eocene. The source rock levels are considerably more frequent in the deepwater domain than in the platforms. The Lower and Upper Jurassic as well as Lower and Middle Cretaceous horizons contain very high levels of organic matter. The offshore seismic shows the transition from the thrusted belt to the foreland basin with a typical triangle zone configuration. Reservoirs are expected in the Cretaceous section covered by seals conformed by early foreland basin sediments of Upper Cretaceous-Paleocene age. Foothill structures has a great potential for hydrocarbon exploration.

  12. The Progreso Basin Province of Northwestern Peru and Southwestern Ecuador: Neogene and Cretaceous-Paleogene Total Petroleum Systems (United States)

    Higley, Debra K.


    The Progreso Basin province (6083) in northwestern Peru and southwestern Ecuador consists of the Paleogene Santa Elena block and Peru Bank, and the Neogene Tumbes-Progreso subbasin. The Santa Elena block and Peru Bank are part of the Cretaceous-Paleogene Total Petroleum System (TPS)(608302), which contains the Cretaceous-Paleogene Santa Elena Block Assessment Unit (60830201). The Tumbes- Progreso subbasin includes the Neogene TPS (608301) and associated Neogene Pull-Apart Basin Assessment Unit (60830101). The complex tectonic history of the Progreso Basin province influenced depositional and erosional patterns across the region, and also the location, timing, and types of seals, traps, possible source and reservoir rocks, and hydrocarbon generation and migration. Marine shales that are interbedded with and overlie reservoir intervals are the probable hydrocarbon source rocks. Timing of hydrocarbon generation and migration was probably Miocene and younger, following creation of the Tumbes-Progreso subbasin by movement along the Dolores-Guayaquil megashear. More than 220 million barrels of oil (MMBO) and 255 billion cubic feet of gas (BCFG) have been produced from the Progreso Basin province. The means of estimated recoverable oil, gas, and natural gas liquids (NGL) resources from undiscovered fields in the province are 237 MMBO, 695 BCFG, and 32 MMB NGL, respectively. The means of estimated recoverable oil, gas, and NGL resources from undiscovered onshore fields are 45 MMBO, 113 BCFG, and 5 MMBNGL, and from undiscovered offshore fields are 192 BBO, 582 BCFG, and 27 MMBNGL. These are USGS grown undiscovered resources that were determined by using a minimum field size of 1 million barrels of oil equivalent.

  13. Quantitative Hydrocarbon Surface Analysis (United States)

    Douglas, Vonnie M.


    The elimination of ozone depleting substances, such as carbon tetrachloride, has resulted in the use of new analytical techniques for cleanliness verification and contamination sampling. The last remaining application at Rocketdyne which required a replacement technique was the quantitative analysis of hydrocarbons by infrared spectrometry. This application, which previously utilized carbon tetrachloride, was successfully modified using the SOC-400, a compact portable FTIR manufactured by Surface Optics Corporation. This instrument can quantitatively measure and identify hydrocarbons from solvent flush of hardware as well as directly analyze the surface of metallic components without the use of ozone depleting chemicals. Several sampling accessories are utilized to perform analysis for various applications.

  14. Miscellaneous hydrocarbon solvents. (United States)

    Bebarta, Vikhyat; DeWitt, Christopher


    The solvents discussed in this article are common solvents not categorized as halogenated, aromatic, or botanical. The solvents discussed are categorized into two groups: hydrocarbon mixtures and single agents. The hydrocarbon mixtures discussed are Stoddard solvent, naphtha, and kerosene. The remaining solvents described are n-hexane, methyl n-butyl ketone, dimethylformamide, dimethyl sulfoxide, and butyl mercaptans. Effects common to this group of agents and their unique effects are characterized. Treatment of exposures and toxic effects of these solvents is described, and physiochemical properties and occupational exposure levels are listed.

  15. Late Cretaceous Aquatic Angiosperms from Jiayin, Heilongjiang,Northeast China

    Institute of Scientific and Technical Information of China (English)

    QUAN Cheng; SUN Ge


    Three taxa of Late Cretaceous aquatic angiosperms, Queruexia angulata (Lesq.) Krysht., Cobbania corrugate. (Lesq.) Stockey et al. and Nelumbites cf. extenuinervis Upchurch et al. from Jiayin of Heilongjiang, NE China, are described in detail. Among them, Cobbania and Nelumbites from the Upper Cretaceous in China are reported for the first time. The aquatic angiosperm assemblage of Queruexia-Cobbania-Nelumbites appears to imply a seasonal, warm and moist environment in the Jiayin area during the Santonian-Campanian time.

  16. Desalination of salt damaged Obernkirchen sandstone by an applied DC field

    DEFF Research Database (Denmark)

    Matyščák, Ondřej; Ottosen, Lisbeth M.; Rörig-Dalgaard, Inge


    Soluble salts are considered as one of the most common causes for decay of building materials. In the present work, an electrokinetic method for desalination of sandstones from a historic warehouse was tested. The sandstones claddings were removed from the warehouse during a renovation action as ...

  17. Mechanism of Suppressing ASR Using Ground Reactive Sandstone Powders instead of Cement

    Institute of Scientific and Technical Information of China (English)

    LI Yang; HE Zhen; HU Shuguang


    In order to understand the effect of powders ground from reactive sandstone replacing cement on reducing or suppressing alkali-silica reaction (ASR), and to identify the mechanism of suppressing ASR by this powders, mortar and paste containing reactive sandstone powders of four replacement levels ranging from 10wt% to 40wt% and four specific surfaces areas ranging from 210 m2/kg to 860 m2/kg were studied. The experimental results showed that incorporation of 40wt%reactive sandstone powders could suppress ASR effectively except for mortar containing reactive sandstone powders with specific surface area of 610 m2/kg, which disagreed with the most results reported that the higher reactive powder specific surface area, the smaller ASR expansion. By means of flame photometry, Fourier transform infrared spectroscopy (FT-IR) and thermo gravimetric analysis (TG), the mechanism of reactive sandstone powders on reducing or suppressing ASR was soluble alkalis type of reactive sandstone powders and the competition of liberating and bonding alkali of cement paste containing reactive sandstone powders,when the ability of alkali bonding was greater than the ability of alkali liberation, ASR caused by reactive sandstone was supressed effectively.

  18. Basin Evolution of the Cretaceous-Early Eocene Xigaze Forearc, Southern Tibet (United States)

    Orme, D. A.; Carrapa, B.; Kapp, P. A.; Gehrels, G. E.; Reiners, P. W.


    An understanding of the processes which control the evolution of forearc basins is important for deciphering the tectonic development of a convergent margin prior to continent-continent suturing. This study presents sedimentologic, modal petrographic and geo-thermochronologic data from the Xigaze forearc basin, preserved along ~ 600 km of the Indus-Yarlung Suture Zone in southern Tibet. From late Cretaceous to early Cenozoic time, subduction of Neo-Tethyan oceanic crust beneath the southern margin of Asia accommodated the northward motion of the Indian craton and formed the Xigaze forearc basin. Following collision with India in the early Cenozoic, the basin transitioned from predominantly marine to non-marine sedimentation and was subsequently uplifted to a mean elevation of 5000 m. Thus, the sedimentary record in the Xigaze forearc preserves information regarding the tectonic evolution of the Indo-Asia continental margin prior to and following collision. We present new measured sections and geo-thermochronologic data from Early Cretaceous to Early Eocene clastic and carbonate sedimentary rocks, preserved in two previously unexplored regions of the forearc, (1) at its western most extent, northwest of Saga, and (2) north of Lhatse. In turn, we compare our results with previously published data in order to synthesize our current understanding of forearc evolution. Strata preserved in the Lhaste region record an initial shallow marine phase of forearc sedimentation (Aptian), but quickly transition to deep marine slope and distal fan turbidite facies (Albian-Campanian). In contrast, facies preserved in the Saga region record a younger shoaling upward marine sequence (Maastrichtian-Ypresian), with the uppermost ~ 400 m consisting of fluvial channel sandstones and red-green paleosols. Facies and depositional environments in the Saga region are highly variable along strike, with turbidites, shelf limestones, estuarine siliciclastics and thick paleosols sequences all

  19. Isotopic and geochemical characterization of groundwater of the Carnot-Berbérati sandstone formation (Western Central African Republic) (United States)

    Djebebe-Ndjiguim, Chantal; Foto, Eric; Backo, Salé; Zoudamba, Narcisse; Basse-Keke, Eric; Nguerekossi, Bruno; Alladin, Oscar; Huneau, Frederic; Garel, Emilie; Celle-Jeanton, Helene; Mabingui, Joseph


    The hydrogeology of the Cretaceous sandstone formations of Carnot-Berbérati (covering an area of 46.000 km2) in the western part of the central African Republic is poorly known. In order to improve the access of local populations to a clean and safe drinking water resource, new investigations have been carried out in order to characterize groundwater in terms of quality, origin, residence time and sustainability. Two sampling campaigns were organized in August 2014 (rainy period) and April 2015 (dry period) on respectively 31 and 43 points including boreholes, wells and river waters. Conventional hydrogeochemical tools in conjunction with isotope hydrology tools were used to evaluate the water types and the anthropogenic fingerprint on groundwater, their recharge processes and the flow organization scheme. Investigations have shown the existence of interesting amounts of groundwater within what seems a single, well hydraulically connected unconfined aquifer of max. 400m thick. Groundwaters are characterized by two main water types: CaMg-HCO3 (for deep boreholes and river waters) and CaMg-ClNO3 (shallow wells). The latter clearly showing the very strong influence of anthropogenic activities (washing, dumps, latrines) in the near vicinity of wells and boreholes used for the drinking water supply. This is also highlighting the total lack of protection zone around the wells and boreholes. Stable isotopes of the water molecule (18O and 2H) are in agreement with a local recharge of groundwater and show a relatively homogeneous composition within the whole aquifer system. Tritium data indicate a modern recharge with a high renewability potential for shallow groundwater but very low tritium levels are observed in the deepest boreholes indicating the probable occurrence of complex flow conditions within the system in some sectors. From these results and because of its extension and storage potential, the Carnot-Berbérati sandstone aquifer appears as a groundwater resource

  20. The sandstone's chromatic alteration of the florentine cultural heritage (United States)

    Vettori, S.; Pecchioni, E.; Cantisani, E.; Ricci, M.; Fratini, F.; Garzonio, C. A.


    Pietra Serena is one of the materials more used in Florentine architecture. It is a sandstone that outcrops in the hills north of the city in the municipality of Fiesole and it has been employed mainly for ornamental purposes. This litotype belongs to the the Macigno Formation (Oligocene Upper- Miocene Lower) which consists of beds of turbiditic sandstones separated by pelitic levels which are the finest components of each single turbidity layer. Petrographically, Pietra Serena can be defined as a medium-coarse-grained greywacke made of quartz, feldspars, micas, fragments of metamorphic and magmatic rocks. The clayey matrix is quite abundant, mainly composed by illite, kaolinite and chlorite-vermiculite (present only in some quarries). It is well known that the processes of decay of the sandstones are related to the type of matrix, the amount of cement, the kind of clay minerals and to the pore size distribution, which lead to water infiltrations, swelling of the clay minerals, separation of the clayey matrix, with resulting exfoliation and peeling of the stone artefacts. Pietra Serena has a bluish-grey colour in fresh cut, but many times it is easily oxidized acquiring an ochraceous-reddish brown colour on buildings. Such changes in colour, appear to be due in part to the oxidation of iron, proceeding very quickly from the surface to the inside, though the cohesion is not affected. It is possible to hypothesize that the chromatic changes not necessarily involve a progressive state of alteration of the artefact, but they may often to represents a natural patina acquired with the time. Nevertheless it is necessary to remember that the oxidized layer and its hardness could also be the result of treatments performed in the past. In Florence, several monuments and buildings are affected by such phenomenon, in particular it is possible to note an intense and diffuse reddish colouring on the Pietra Serena utilized for columns and for façade's decorations. In this work

  1. On the origin and glacial transport of erratics of Jotnian sandstone in southwestern Finland

    Directory of Open Access Journals (Sweden)

    Donner, J.


    Full Text Available Late Proterozoic Jotnian sandstone erratics were transported during the last Quaternary glaciation from the source area in Satakunta at the coast of southwestern Finland and the bottom of the Bothnian Sea to the southeast as far as Estonia, Latvia and Russia. The frequencies of the sandstone erratics show that they were transported greater distances than indicators of other rocks in the southern parts of Finland. In addition, high frequencies in small areas, south of Salo and in Bromarv, indicate that there are or were small separate source areas of Jotnian sandstone outside the main area. This is supported by the distribution of erratics of Cambrian sandstone and Ordovician sedimentary rocks in the same area. The tracing of possible small occurrences of Jotnian sandstone or Palaeozoic rocks is, however, difficult in an area with numerous faults and fracture zones in the Precambrian bedrock, where the depressions are covered by thick Quaternary drift.

  2. Late Cretaceous Volcaniclastics in NW Turkey (United States)

    Boehm, Katharina; Wolfgring, Erik; Omer Yilmaz, Ismail; Tüysüz, Okan; Wagreich, Michael


    On the southwestern coast of the Black Sea, in the western Pontides Upper Cretaceous tuff layers are present. The tuffs are intercalated with limestones, marls and turbidites and were investigated with focus on their geochemistry, to get new insights to the arrangement of terranes and ocean basins at this time. In the region two Upper Cretaceous volcanic units can be distinguished, separated by distinct red pelagic limestone successions, belonging to the Unaz Formation. The lower volcanic unit is named Dereköy Formation and is Turonian to Santonian in age. It is thought to be deposited within extension structures, contemporaneously with rifting in the western Black Sea basin. The upper volcanic unit is called Cambu Formation. According to biostratigraphic data it is deposited throughout Campanian, when spreading in the western Black Sea basin started. Interpreted as submarine deposits, element mobility has to be taken into account when interpreting geochemical ICP-MS data of the volcaniclastics. Multiple discrimination diagrams with suitable proxies elucidate the type of volcanism and contribute to reconstruction of the tectonic setting. The classified rock types range from basaltic to rhyodacitic in both volcanic formations. Basically degree of differentiation and alkalinity are the parameters looked at, when determining rock types of the volcanic eruption. Further volcanic series are specified as calc-alkaline to shoshonitic. Moreover, a volcanic arc setting seems to be the most likely case, following several discrimination diagrams, as well as normalized multi-element plots. This tectonic setting can be discussed in connection with paleo-tectonic reconstructions. Most cited in literature nowadays are models favoring a northward subduction of the northern branch of Neotethys, creating an extensional setting north of the Pontides. This kind of back arc extension is interpreted as the reason of a southward drift of the Istanbul continental fragment from Eurasia

  3. Cathodoluminescence investigations on quartz cement in the sandstones of Khabour Formation from Iraqi Kurdistan Region, Northern Iraq

    DEFF Research Database (Denmark)

    Omer, Muhamed Fakhri; Friis, Henrik


    The Ordovician deltaic to shallow marine Khabour Formation in Northern Iraq consists mainly of sandstone with minor siltstone and interbedded shale. The sandstones are pervasively cemented by quartz that resulted in very little preserved primary porosity. Cathodoluminescence and petrographic stud...

  4. Stratigraphic framework and coal correlation of the Upper Cretaceous Fruitland Formation, Bisti-Ah-Shi-Sle-Pah area, San Juan Basin, New Mexico (United States)

    Flores, Romeo M.; Erpenbeck, Michael F.


    This report illustrates and describes the detailed stratigraphic framework and coal correlation of the Upper Cretaceous Fruitland Formation exposed in isolated badlands and along washes within a 20-mile outcrop belt in the Bisti-Ah-Shi-Sle-Pah area, southwestern San Juan Basin, Nex Mexico (see index). The stratigraphic framework showing the vertical and lateral distributions of rock types and the lateral continuity of coal beds is illustrated in cross sections. The cross sections were constructed from 112 stratigraphic sections measured at an average distance of 0.4 mi apart. Each section contained key marker beds (sandstone, coal, and tonstein) that were physically traced to adjacent sections. Each measured section was "hung" on multiple marker beds arranged in a geometric best-fit method that accounts for the differential compaction and facies associations of the deposits. 

  5. Apparatus and methods for hydrocarbon extraction (United States)

    Bohnert, George W.; Verhulst, Galen G.


    Systems and methods for hydrocarbon extraction from hydrocarbon-containing material. Such systems and methods relate to extracting hydrocarbon from hydrocarbon-containing material employing a non-aqueous extractant. Additionally, such systems and methods relate to recovering and reusing non-aqueous extractant employed for extracting hydrocarbon from hydrocarbon-containing material.

  6. Optrode for sensing hydrocarbons (United States)

    Miller, Holly; Milanovich, Fred P.; Hirschfeld, Tomas B.; Miller, Fred S.


    A two-phase system employing the Fujiwara reaction is provided for the fluorometric detection of halogenated hydrocarbons. A fiber optic is utilized to illuminate a column of pyridine trapped in a capillary tube coaxially attached at one end to the illuminating end of the fiber optic. A strongly alkaline condition necessary for the reaction is maintained by providing a reservoir of alkali in contact with the column of pyridine, the surface of contact being adjacent to the illuminating end of the fiber optic. A semipermeable membrane caps the other end of the capillary tube, the membrane being preferentially permeable to the halogenated hydrocarbon and but preferentially impermeable to water and pyridine. As the halogenated hydrocarbon diffuses through the membrane and into the column of pyridine, fluorescent reaction products are formed. Light propagated by the fiber optic from a light source, excites the fluorescent products. Light from the fluorescence emission is also collected by the same fiber optic and transmitted to a detector. The intensity of the fluorescence gives a measure of the concentration of the halogenated hydrocarbons.

  7. Electrokinetic desalination of sandstones for NaCl removal

    DEFF Research Database (Denmark)

    Ottosen, Lisbeth M.; Christensen, Iben V.


    of reliable methods to remove the damaging salts in order to stop the decay. Electrokinetic desalination of fired clay bricks have previously shown efficient in laboratory scale and in the present work the method is tested for desalination of Cotta and Posta sandstones, which both have lower porosity than...... the bricks studied. The stones were contaminated with NaCl by submersion prior to the desalination experiments, where an electric DC field was applied to the stones from electrodes placed in clay poultice. Two poultice types were tested: calcareous clay used brick production and a mixture of kaolinite...... surface) applied. At the end of all desalination experiments the water content in the poultice at the cathode was higher than in the poultice at the anode, revealing electroosmotic water transport. The water profiles in the stones, however, did not indicate electoosmosis as they were quite uniform within...

  8. Process-dependent residual trapping of CO2 in sandstone (United States)

    Zuo, Lin; Benson, Sally M.


    This paper demonstrates that the nature and extent of residual CO2 trapping depend on the process by which the CO2 phase is introduced into the rock. We compare residual trapping of CO2 in Berea Sandstone by imbibing water into a core containing either exsolved CO2 or CO2 introduced by drainage. X-ray computed tomography measurements are used to map the spatial distribution of CO2 preimbibition and postimbibition. Unlike during drainage where the CO2 distribution is strongly influenced by the heterogeneity of the rock, the distribution of exsolved CO2 is comparatively uniform. Postimbibition, the CO2 distribution retained the essential features for both the exsolved and drainage cases, but twice as much residual trapping is observed for exsolved CO2 even with similar preimbibition gas saturations. Residually trapped exsolved gas also disproportionately reduced water relative permeability. Development of process-dependent parameterization will help better manage subsurface flow processes and unlock benefits from gas exsolution.

  9. Downslope coarsening in aeolian grainflows of the Navajo Sandstone (United States)

    Loope, David B.; Elder, James F.; Sweeney, Mark R.


    Downslope coarsening in grainflows has been observed on present-day dunes and generated in labs, but few previous studies have examined vertical sorting in ancient aeolian grainflows. We studied the grainflow strata of the Jurassic Navajo Sandstone in the southern Utah portion of its outcrop belt from Zion National Park (west) to Coyote Buttes and The Dive (east). At each study site, thick sets of grainflow-dominated cross-strata that were deposited by large transverse dunes comprise the bulk of the Navajo Sandstone. We studied three stratigraphic columns, one per site, composed almost exclusively of aeolian cross-strata. For each column, samples were obtained from one grainflow stratum in each consecutive set of the column, for a total of 139 samples from thirty-two sets of cross-strata. To investigate grading perpendicular to bedding within individual grainflows, we collected fourteen samples from four superimposed grainflow strata at The Dive. Samples were analyzed with a Malvern Mastersizer 2000 laser diffraction particle analyser. The median grain size of grainflow samples ranges from fine sand (164 μm) to coarse sand (617 μm). Using Folk and Ward criteria, samples are well-sorted to moderately-well-sorted. All but one of the twenty-eight sets showed at least slight downslope coarsening, but in general, downslope coarsening was not as well-developed or as consistent as that reported in laboratory subaqueous grainflows. Because coarse sand should be quickly sequestered within preserved cross-strata when bedforms climb, grain-size studies may help to test hypotheses for the stacking of sets of cross-strata.

  10. Reservoir characterization of Pennsylvanian Sandstone Reservoirs. Annual report

    Energy Technology Data Exchange (ETDEWEB)

    Kelkar, M.


    This annual report describes the progress during the second year of a project on Reservoir Characterization of Pennsylvanian Sandstone Reservoirs. The report is divided into three sections: (i) reservoir description and scale-up procedures; (ii) outcrop investigation; (iii) in-fill drilling potential. The first section describes the methods by which a reservoir can be characterized, can be described in three dimensions, and can be scaled up with respect to its properties, appropriate for simulation purposes. The second section describes the progress on investigation of an outcrop. The outcrop is an analog of Bartlesville Sandstone. We have drilled ten wells behind the outcrop and collected extensive log and core data. The cores have been slabbed, photographed and the several plugs have been taken. In addition, minipermeameter is used to measure permeabilities on the core surface at six inch intervals. The plugs have been analyzed for the permeability and porosity values. The variations in property values will be tied to the geological descriptions as well as the subsurface data collected from the Glen Pool field. The third section discusses the application of geostatistical techniques to infer in-fill well locations. The geostatistical technique used is the simulated annealing technique because of its flexibility. One of the important reservoir data is the production data. Use of production data will allow us to define the reservoir continuities, which may in turn, determine the in-fill well locations. The proposed technique allows us to incorporate some of the production data as constraints in the reservoir descriptions. The technique has been validated by comparing the results with numerical simulations.

  11. Microbial Penetration through Nutrient-Saturated Berea Sandstone. (United States)

    Jenneman, G E; McInerney, M J; Knapp, R M


    Penetration times and penetration rates for a motile Bacillus strain growing in nutrient-saturated Berea sandstone cores were determined. The rate of penetration was essentially independent of permeabilities above 100 mdarcys and rapidly declined for permeabilities below 100 mdarcys. It was found that these penetration rates could be grouped into two statistically distinct classes consisting of rates for permeabilities above 100 mdarcys and rates for those below 100 mdarcys. Instantaneous penetration rates were found to be zero order with respect to core length for cores with permeabilities above 100 mdarcys and first order with respect to core length for cores with permeabilities below 100 mdarcys. The maximum observed penetration rate was 0.47 cm . h, and the slowest was 0.06 cm . h; however, these rates may be underestimates of the true penetration rate, since the observed rates included the time required for growth in the flask as well as the core. The relationship of penetration time to the square of the length of the core suggested that cells penetrated high-permeability cores as a band and low-permeability cores in a diffuse fashion. The motile Enterobacter aerogenes strain penetrated Berea sandstone cores three to eight times faster than did the nonmotile Klebsiella pneumoniae strain when cores of comparable length and permeability were used. A penetration mechanism based entirely on motility predicted penetration times that were in agreement with the observed penetration times for motile strains. The fact that nonmotile strains penetrated the cores suggested that filamentous or unrestricted growth, or both, may also be important.


    Institute of Scientific and Technical Information of China (English)

    冯杨伟; 屈红军; 张功成; 范玉海; 关利群


    . Correspondingly there are three suits of sedimentary sequences. Most of hydrocarbon is accumulated in the Mesozoic, with gas in the outer part and lower sequence, and oil in the inner part and upper sequence. 3 types of source rocks are recognized. They are the Triassic lacustrine shale, Jurassic paralic carbonaceous argilite, coal bearing strata and marine shale, and Cretaceous marine shale. Most of the source rocks have great capacity of gas generation. The source rocks can be summarized into four models. The main reservoir is the marine sandstone deposited in the rift stage, and the Cretaceous turbidites formed in the passive continental margin stage is a potential reservoir. The Lower Cretaceous marine shale is the main seal covering the whole region. From the view point of petroleum system, there are three reservoir-seal assemblages in the region including the marine reservoir-seal assemblage, paralic reservoir-seal assemblage and continental reservoir-seal assemblage, and the paralic reservoir-seal assemblage dominates. The major passes for hydrocarbon migration include structural ridges, faults, and unconformities. Overpressure, fault and unconformity are the major driving factors of hydrocarbon migration. In this study area major plays always occur in the lower sequence near the source with the upper parts as reservoir and seal.

  13. Mantle hydrocarbons: abiotic or biotic? (United States)

    Sugisaki, R; Mimura, K


    Analyses of 227 rocks from fifty localities throughout the world showed that mantle derived rocks such as tectonized peridotites in ophiolite sequences (tectonites) arid peridotite xenoliths in alkali basalts contain heavier hydrocarbons (n-alkanes), whereas igneous rocks produced by magmas such as gabbro arid granite lack them. The occurrence of hydrocarbons indicates that they were not derived either from laboratory contamination or from held contamination; these compounds found in the mantle-derived rocks are called here "mantle hydrocarbons." The existence of hydrocarbons correlates with petrogenesis. For example, peridotite cumulates produced by magmatic differentiation lack hydrocarbons whereas peridotite xenoliths derived from the mantle contain them. Gas chromatographic-mass spectrometric records of the mantle hydrocarbons resemble those of aliphatics in meteorites and in petroleum. Features of the hydrocarbons are that (a) the mantle hydrocarbons reside mainly along grain boundaries and in fluid inclusions of minerals; (b) heavier isoprenoids such as pristane and phytane are present; and (c) delta 13C of the mantle hydrocarbons is uniform (about -27%). Possible origins for the mantle hydrocarbons are as follows. (1) They were in organically synthesized by Fischer-Tropsch type reaction in the mantle. (2) They were delivered by meteorites and comets to the early Earth. (3) They were recycled by subduction. The mantle hydrocarbons in the cases of (1) and (2) are abiogenic and those in (3) are mainly biogenic. It appears that hydrocarbons may survive high pressures and temperatures in the mantle, but they are decomposed into lighter hydrocarbon gases such as CH4 at lower pressures when magmas intrude into the crust; consequently, peridotite cumulates do not contain heavier hydrocarbons but possess hydrocarbon gases up to C4H10.

  14. Volcanostratigraphy, petrography and petrochemistry of Late Cretaceous volcanic rocks from the Görele area (Giresun, NE Turkey) (United States)

    Oguz, Simge; Aydin, Faruk; Baser, Rasim


    In this study, we have reported for lithological, petrographical and geochemical features of late Cretaceous volcanic rocks from the Çanakçı and the Karabörk areas in the south-eastern part of Görele (Giresun, NE Turkey) in order to investigate their origin and magmatic evolution. Based on the previous ages and recent volcano-stratigraphic studies, the late Cretaceous time in the study area is characterized by an intensive volcanic activity that occurred in two different periods. The first period of the late Cretaceous volcanism (Cenomanian-Santonian; 100-85 My), conformably overlain by Upper Jurassic-Lower Cretaceous massive carbonates (Berdiga Formation), is represented by bimodal units consisting of mainly mafic rock series (basaltic-andesitic lavas and hyaloclastites, dikes and sills) in the lower part (Çatak Formation), and felsic rock series (dacitic lavas and hyaloclastites, crystal- and pyrite-bearing tuffs) in the upper part (Kızılkaya Formation). The second period of the late Cretaceous volcanism (Santonian-Late Campanian; 85-75 Ma) is also represented by bimodal character and again begins with mafic rock suites (basaltic-basaltic andesitic lavas and hyaloclastites) in the lower part (Çağlayan Formation), and grades upward into felsic rock suites (biotite-bearing rhyolitic lavas, ignimbrites and hyaloclastites) through the upper part (Tirebolu Formation). These bimodal units are intercalated with volcanic conglomerates-sandstones, claystones, marl and red pelagic limestones throughout the volcanic sequence, and the felsic rock series have a special important due to hosting of volcanogenic massive sulfide deposits in the region. All volcano-sedimentary units are covered by Tonya Formation (Late Campanian-Paleocene) containing calciturbidites, biomicrites and clayey limestones. The mafic rocks in the two volcanic periods generally include basalt, basaltic andesite and minor andesite, whereas felsic volcanics of the first period mainly consists of

  15. Geochemical Variations in Hydrocarbon Components Distribution in a Prograding Deltaic Sequence: A Case Study of the Baram Delta, Offshore Sarawak Basin, Malaysia

    Directory of Open Access Journals (Sweden)

    J. Ben-Awuah


    Full Text Available Studies on hydrocarbon distribution have evolved from basic reservoir characterization to complex studies today involving the interactions between oil components and clay minerals and sequential extraction studies on hydrocarbon extracts in reservoir rocks. Findings from such studies include the discovery of variations in oil fractions in reservoirs such as adsorbed oil and free oil. The theory that first oil charge preferentially interacts with clay minerals occurring in pores and as coatings in reservoirs was also proposed by some researchers. Despite, all these studies some aspects of variations in the composition of hydrocarbons in reservoir rocks still need to be investigated further. This study has been carried out particularly because the qualitative and quantitative composition of aromatic and aliphatic components of hydrocarbons in terms of the presence and quantities of hydrocarbon functional groups and how they relate to hydrocarbon migration have not been exhaustively discussed. This study uses Ultra-Violet visible light (UV-vis and Fourier Transform Infra Red (FTIR to characterize variations in hydrocarbon distribution in reservoir quality sandstones from three fields namely BD01, BD02 and BD03 in the Baram Delta, offshore Sarawak and to deduce how these variations relate to differential migration patterns in hydrocarbons. Hydrocarbon extraction was done in the ultra vilolet visible (UV-vis experiment using 0.1M sodium pyrophosphate as solvent whereas in the Fourier Transform Infra Red (FTIR, the experiment was done on very fine powdered samples of the sandstones. Results from both the UV-vis and FTIR experiments indicate a dominance of aromatic functional groups in the samples. Most of the samples have E4/E6 ratio of more than 1 which indicates a high degree of aromacity. The BD01 field sandstones with a maximum porosity of 32% has the highest average E4/E6 ratio of 1.21, followed by the BD02 field sandstones with a maximum

  16. Detrital and delayed CRM acquisition in redbeds: the Lower Cretaceous Zicapa Formation, southern Mexico (United States)

    Sierra-Rojas, M. I.; Molina-Garza, R. S.


    The Lower Cretaceous Zicapa Formation is characterized by hematite-cemented clastic rocks interbeded with limestone and volcanic rocks, deposited in continental to transitional-marine environments. The paleomagnetic data presented here correspond to exposures in the San Juan de las Joyas locality, in the Mixteca terrain of southern Mexico. Hematite cement is derived from an important input of primary volcanic material contemporaneous with deposition and from mafic to intermediate metavolcanic sources. We sampled 17 sites in a 110 m segment of continuous depositation of fine to coarse, red to purple, lithic sandstone and siltstone. The natural magnetization is multivectorial, and AF demagnetization suggests that it resides primarily in hematite. One magnetization component is unblocked below 200C is north-directed and positive. A low-unblocking temperature magnetization (LT) is unblocked between 250-500C, and a high-unblocking-temperature component (HT) is defined between about 600-650C. Both, the LT and HT components are dual-polarity and form nearly antipodal groups of WNW (ESE) directions. NRM demagnetization and rock magnetic data suggest the presence of two kinds of particles carrying the LT and HT components. Polarity changes in the section sampled are characterized by sites that register in the HT component the magnetic field previous to the transition of polarity (which is detrital magnetization residing in specular hematite), whilst the LT registers the magnetic field after the polarity transition. Typically, in the overlying (post-transition) site the LT and HT components are of the same polarity. This suggests that the LT component is a late (or delayed) CRM that resides in small particles of pigmentary hematite. The accepted sites yield a tilt corrected mean of declination Dec= 273 degrees, inclination Inc= 33.1 degrees (α95=11.7 y k=18).The mean directions are discordant with respect to expected North America reference for Early Cretaceous indicating a

  17. Bacterial sources for phenylalkane hydrocarbons

    Energy Technology Data Exchange (ETDEWEB)

    Ellis, L.; Winans, R.E. [Argonne National Lab., IL (United States); Langworthy, T. [Univ. of South Dakota, Vermillion, SD (United States)


    The presence of phenylalkane hydrocarbons in geochemical samples has been the source of much controversy. Although an anthropogenic input from detergent sources always appears likely, the distribution of phenylalkane hydrocarbons in some cases far exceeding that attributed to detergent input has led to a reappraisal of this view. Indeed, recent work involving analysis of the lipid hydrocarbon extracts from extant Thermoplasma bacteria has revealed the presence of phenylalkane hydrocarbons. The presence of phenylalkane hydrocarbons in sedimentary organic matter may therefore represent potential biological markers for thermophilic bacteria.

  18. Microbial degradation of petroleum hydrocarbons. (United States)

    Varjani, Sunita J


    Petroleum hydrocarbon pollutants are recalcitrant compounds and are classified as priority pollutants. Cleaning up of these pollutants from environment is a real world problem. Bioremediation has become a major method employed in restoration of petroleum hydrocarbon polluted environments that makes use of natural microbial biodegradation activity. Petroleum hydrocarbons utilizing microorganisms are ubiquitously distributed in environment. They naturally biodegrade pollutants and thereby remove them from the environment. Removal of petroleum hydrocarbon pollutants from environment by applying oleophilic microorganisms (individual isolate/consortium of microorganisms) is ecofriendly and economic. Microbial biodegradation of petroleum hydrocarbon pollutants employs the enzyme catalytic activities of microorganisms to enhance the rate of pollutants degradation. This article provides an overview about bioremediation for petroleum hydrocarbon pollutants. It also includes explanation about hydrocarbon metabolism in microorganisms with a special focus on new insights obtained during past couple of years. Copyright © 2016 Elsevier Ltd. All rights reserved.

  19. Paleointensity of the geomagnetic field in the Cretaceous (from Cretaceous rocks of Mongolia) (United States)

    Shcherbakova, V. V.; Kovalenko, D. V.; Shcherbakov, V. P.; Zhidkov, G. V.


    A representative collection of Cretaceous rocks of Mongolia is used for the study of the magnetic properties of the rocks and for determination of the paleodirections and paleointensities H anc of the geomagnetic field. The characteristic NRM component in the samples is recognized in the temperature interval from 200 to 620-660°C. The values of H anc are determined by the Thellier-Coe method with observance of all present-day requirements regarding the reliability of such kind of results. Comparison of data in the literature on paleointensity in the Cretaceous superchron and in the Miocene supports the hypothesis of the inverse correlation between the average intensity of the paleofield and the frequency of geomagnetic reversals. The increase in the average intensities is accompanied by an appreciable increase in the variance of the virtual dipole moment (VDM). We suggest that the visible increase in the average VDM value in the superchron is due to the greater variability of VDM in this period compared to the Miocene.

  20. Superconductivity in aromatic hydrocarbons

    Energy Technology Data Exchange (ETDEWEB)

    Kubozono, Yoshihiro, E-mail: [Research Laboratory for Surface Science, Okayama University, Okayama 700-8530 (Japan); Research Center of New Functional Materials for Energy Production, Storage and Transport, Okayama University, Okayama 700-8530 (Japan); Japan Science and Technology Agency, ACT-C, Kawaguchi 332-0012 (Japan); Goto, Hidenori; Jabuchi, Taihei [Research Laboratory for Surface Science, Okayama University, Okayama 700-8530 (Japan); Yokoya, Takayoshi [Research Laboratory for Surface Science, Okayama University, Okayama 700-8530 (Japan); Research Center of New Functional Materials for Energy Production, Storage and Transport, Okayama University, Okayama 700-8530 (Japan); Kambe, Takashi [Department of Physics, Okayama University, Okayama 700-8530 (Japan); Sakai, Yusuke; Izumi, Masanari; Zheng, Lu; Hamao, Shino; Nguyen, Huyen L.T. [Research Laboratory for Surface Science, Okayama University, Okayama 700-8530 (Japan); Sakata, Masafumi; Kagayama, Tomoko; Shimizu, Katsuya [Center of Science and Technology under Extreme Conditions, Osaka University, Osaka 560-8531 (Japan)


    Highlights: • Aromatic superconductor is one of core research subjects in superconductivity. Superconductivity is observed in certain metal-doped aromatic hydrocarbons. Some serious problems to be solved exist for future advancement of the research. This article shows the present status of aromatic superconductors. - Abstract: ‘Aromatic hydrocarbon’ implies an organic molecule that satisfies the (4n + 2) π-electron rule and consists of benzene rings. Doping solid aromatic hydrocarbons with metals provides the superconductivity. The first discovery of such superconductivity was made for K-doped picene (K{sub x}picene, five benzene rings). Its superconducting transition temperatures (T{sub c}’s) were 7 and 18 K. Recently, we found a new superconducting K{sub x}picene phase with a T{sub c} as high as 14 K, so we now know that K{sub x}picene possesses multiple superconducting phases. Besides K{sub x}picene, we discovered new superconductors such as Rb{sub x}picene and Ca{sub x}picene. A most serious problem is that the shielding fraction is ⩽15% for K{sub x}picene and Rb{sub x}picene, and it is often ∼1% for other superconductors. Such low shielding fractions have made it difficult to determine the crystal structures of superconducting phases. Nevertheless, many research groups have expended a great deal of effort to make high quality hydrocarbon superconductors in the five years since the discovery of hydrocarbon superconductivity. At the present stage, superconductivity is observed in certain metal-doped aromatic hydrocarbons (picene, phenanthrene and dibenzopentacene), but the shielding fraction remains stubbornly low. The highest priority research area is to prepare aromatic superconductors with a high superconducting volume-fraction. Despite these difficulties, aromatic superconductivity is still a core research target and presents interesting and potentially breakthrough challenges, such as the positive pressure dependence of T{sub c} that is clearly

  1. Alluvial fan facies of the Yongchong Basin: Implications for tectonic and paleoclimatic changes during Late Cretaceous in SE China (United States)

    Chen, Liuqin; Steel, Ronald J.; Guo, Fusheng; Olariu, Cornel; Gong, Chenglin


    Late Cretaceous continental redbeds, the Guifeng Group of the Yongchong Basin in SE China have been investigated to conduct detailed fan facies description and interpretation. Tectonic activities determined the alluvial fan development along the basin margin, but the alluvial facies was linked with paleoclimate changes. The Guifeng Group is divided into the Hekou, Tangbian and Lianhe formations in ascending order. The Hekou conglomerates are typically polymict, moderately sorted with erosional bases, cut-and-fill features, normal grading and sieve deposits, representing dominant stream-flows on alluvial fans during the initial opening stage of the basin infill. The Tangbian Formation, however, is characterized by structureless fine-grained sediments with dispersed coarse clasts, and couplets of conglomerate and sandstone or siltstone and mudstone, recording a change to a playa and ephemeral lake environments with occasional stream flooding, thus indicating a basin expanding stage. The hallmark of the Lianhe Formation is disorganized, poorly sorted conglomerates lack of erosional bases, and a wide particle-size range from clay to boulders together reflect mud-rich debris-flows accumulating on fans, likely related to reactivation of faulting along the northwestern mountain fronts during a post-rift stage. The depositional system changes from stream-flows up through playa with ephemeral streams to debris-flows during the accumulation of the three formations are thus attributed to different source rocks and climatic conditions. Therefore, the fluvial-dominated fans of the Hekou Formation recorded a subhumid paleoclimate (Coniacian-Santonian Age). The dominant semiarid climate during the Campanian Age produced abundant fine-grained sediments in the playa and ephemeral lake environments of the Tangbian Formation. A climatic change towards more humidity during the late stage of the Guifeng Group (Maastrichtian Age) probably yielded high deposition rate of coarse clasts in

  2. New Cretaceous and Tertiary Paleomagnetic Results from the Central Tibet Conjugate Fault Zone (United States)

    Foster, S.; Finn, D.; Zhao, X.; Coe, R. S.; Spinardi, F.; Lippert, P. C.; Yin, A.; Wang, C.; Meng, J.; Zhang, S.; Li, H.


    measure the anisotropy of magnetic susceptibility to evaluate the potential effects on remanent magnetic directions. Characteristic directions from gray siltstones from the Tertiary Nubao Formation show a small (~15°) CW rotation when compared to Eurasian reference poles. The sampling location is north of the Zagaya fault in the Qiangtang terrane. Characteristic directions from Langshan Formation samples collected this Spring of 2012 show small (<10°) CCW rotation. These samples were collected east of the Seling Co in the Lhasa terrane. The small observed rotation from these new paleomagnetic data contradicts the preexisting model that predicts faults initiated 30° from the convergence direction and subsequently rotated by 40°. These data are only preliminary and from a subset of the larger Spring 2012 collection. We also have sampled late Tertiary red and gray sandstones and siltstones north of the Seling Co, and later Cretaceous red-purple sandstones from Jingzhushan Formation east of the Seling Co. Detailed laboratory results from our new Spring 2012 sample collection and a summary of our existing results will be presented at AGU.

  3. Biostratigraphy of the Upper Cretaceous deposits in north of Birjand, (Shushud section

    Directory of Open Access Journals (Sweden)

    farah jalili


    sequence could be divided into two informal members. The lower member is formed by intercalation of marl, shaly marl, thin bedded limestone and sandstone. The upper member includes medium to thick bedded limestone, medium bedded sandy limestone that changes to red sandstone. Moreover, in the upper part medium bedded limestone and sandy limestone are predominant. The upper boundary with Eocene deposits is unconformable. In the lower member, the following assemblage is identified; Abathomphalus sp., Bolivinoides draco draco, Dentalina granti, Gavelinella sp., Globotruncanita conica, Globotruncana arca, Globotruncana sp., Globotruncanita stuarti, Heterohelix sp., Heterohelix globulosa, Marssonella turris, Neoflabellina cf. permutata, Pseudotextularia sp., Pseudotextularia elegans, Pseudotextularia nuttalli, Planomalina sp., Schackonia sp. The following assemblage is also recognised in the upper member; Bolivinita planate, Goupilloudina iranica, Goupilloudina shirazensis, Globotruncanita stuarti, Heterohelix globulosa, Iranites ornatus, Lepidorbitoides socialis, Lepidorbitoides sp., Nezzazzata sp., Orbitoides media, Omphalocyclus macroporus, Orbitoides tissoti, Orbitoides apiculata. Pseudorotalia persica, Pseudotextularia elegans, Sulcoperculina sp., Siderolites calcitrapoides, Sirtina sp., Textularid. Globigerinelloides sp., Globotruncanita stuarti, Iranites ornatus, Lepidorbitoides socialis, Lepidorbitoides sp., Nezzazzata sp., Omphalocyclus macroporus, Orbitoides media, Pseudorotalia persica. Above the deposits that attributed to Cretaceous with a basal conglomerate, there is a sequence that the following foraminifera are identified; Alveolina pasticillata, Alveolina leupoldi, Alveolina aragonensis, Alveolina aff. pisella Alveolina (Glomalveolina primaeva, Alveolina aff. rutimeyeri, Alveolina (Glomalveolina sp., Biloculina sp., Miscellanea aff. iranica, Miscellanea sp., Nummulites convexa, Nummulites cf. guettardi. Based on the identified benthic and palnktonic foraminifera

  4. Acoustic emission signals frequency-amplitude characteristics of sandstone after thermal treated under uniaxial compression (United States)

    Kong, Biao; Wang, Enyuan; Li, Zenghua; Wang, Xiaoran; Niu, Yue; Kong, Xiangguo


    Thermally treated sandstone deformation and fracture produced abundant acoustic emission (AE) signals. The AE signals waveform contained plentiful precursor information of sandstone deformation and fracture behavior. In this paper, uniaxial compression tests of sandstone after different temperature treatments were conducted, the frequency-amplitude characteristics of AE signals were studied, and the main frequency distribution at different stress level was analyzed. The AE signals frequency-amplitude characteristics had great difference after different high temperature treatment. Significant differences existed of the main frequency distribution of AE signals during thermal treated sandstone deformation and fracture. The main frequency band of the largest waveforms proportion was not unchanged after different high temperature treatments. High temperature caused thermal damage to the sandstone, and sandstone deformation and fracture was obvious than the room temperature. The number of AE signals was larger than the room temperature during the initial loading stage. The low frequency AE signals had bigger proportion when the stress was 0.1, and the maximum value of the low frequency amplitude was larger than high frequency signals. With the increase of stress, the low and high frequency AE signals were gradually increase, which indicated that different scales ruptures were broken in sandstone. After high temperature treatment, the number of high frequency AE signals was significantly bigger than the low frequency AE signals during the latter loading stage, this indicates that the small scale rupture rate of recurrence and frequency were more than large scale rupture. The AE ratio reached the maximum during the sandstone instability failure period, and large scale rupture was dominated in the failure process. AE amplitude increase as the loading increases, the deformation and fracture of sandstone was increased gradually. By comparison, the value of the low frequency

  5. Fracturing and Damage to Sandstone Under Coupling Effects of Chemical Corrosion and Freeze-Thaw Cycles (United States)

    Han, Tielin; Shi, Junping; Cao, Xiaoshan


    Rapid freeze-thaw (FT) cycles were adopted to explore the damage deterioration mechanism and mechanical properties of sandstone specimens under the coupling effects of different chemical solutions and FT cycles. The variation regularities of the FT cycles and physical and mechanical properties of sandstone specimens immersed in different chemical solutions were analyzed by using sandstone sampled from a Chinese riverbank slope. The damage variable based on porosity variation was used in the quantitative analysis of the damage to the sandstone under the coupling effects of chemical corrosion and FT cycles. Experimental results showed that the sandstone specimens weakened substantially under those effects. Their fracture toughness K IC, splitting tensile strength, and compressive strength showed a similar deteriorating trend with various numbers of FT cycles. However, a difference exists in the deterioration degree of their mechanical parameters, i.e., the deterioration degree of their fracture toughness K IC is the greatest followed by that of splitting tensile strength, and that of compressive strength is relatively small. Strong acid solutions may aggravate the deterioration of FT damage in sandstones, but at the early stage of the experiment, strong alkaline solutions inhibited sandstone damage deterioration. However, the inhibiting effect disappeared when the number of FT cycles exceeded 25. The different chemical solutions had a different effect on the FT damage degree of the sandstone specimens; for example, SO4 2- ions had a greater effect on FT damage than did HCO3 - ions. Water-chemical solutions and FT cycles promote each other in deteriorating rocks and simultaneously affect the damage deterioration degree of sandstones.

  6. Membrane separation of hydrocarbons (United States)

    Chang, Y. Alice; Kulkarni, Sudhir S.; Funk, Edward W.


    Mixtures of heavy oils and light hydrocarbons may be separated by passing the mixture through a polymeric membrane. The membrane which is utilized to effect the separation comprises a polymer which is capable of maintaining its integrity in the presence of hydrocarbon compounds and which has been modified by being subjected to the action of a sulfonating agent. Sulfonating agents which may be employed will include fuming sulfuric acid, chlorosulfonic acid, sulfur trioxide, etc., the surface or bulk modified polymer will contain a degree of sulfonation ranging from about 15 to about 50%. The separation process is effected at temperatures ranging from about ambient to about C. and pressures ranging from about 50 to about 1000 psig.

  7. Rates of morphological evolution are heterogeneous in Early Cretaceous birds. (United States)

    Wang, Min; Lloyd, Graeme T


    The Early Cretaceous is a critical interval in the early history of birds. Exceptional fossils indicate that important evolutionary novelties such as a pygostyle and a keeled sternum had already arisen in Early Cretaceous taxa, bridging much of the morphological gap between Archaeopteryx and crown birds. However, detailed features of basal bird evolution remain obscure because of both the small sample of fossil taxa previously considered and a lack of quantitative studies assessing rates of morphological evolution. Here we apply a recently available phylogenetic method and associated sensitivity tests to a large data matrix of morphological characters to quantify rates of morphological evolution in Early Cretaceous birds. Our results reveal that although rates were highly heterogeneous between different Early Cretaceous avian lineages, consistent patterns of significantly high or low rates were harder to pinpoint. Nevertheless, evidence for accelerated evolutionary rates is strongest at the point when Ornithuromorpha (the clade comprises all extant birds and descendants from their most recent common ancestors) split from Enantiornithes (a diverse clade that went extinct at the end-Cretaceous), consistent with the hypothesis that this key split opened up new niches and ultimately led to greater diversity for these two dominant clades of Mesozoic birds.

  8. Facies architecture of the Bluejacket Sandstone in the Eufaula Lake area, Oklahoma: Implications for the reservoir characterization of the Bartlesville Sandstone

    Energy Technology Data Exchange (ETDEWEB)

    Ye, Liangmiao; Yang, Kexian [Univ. of Tulsa, OK (United States)


    Outcrop studies of the Bluejacket Sandstone (Middle Pennsylvanian) provide significant insights to reservoir architecture of the subsurface equivalent Bartlesville Sandstone. Quarry walls and road cuts in the Lake Eufaula area offer excellent exposures for detailed facies architectural investigations using high-precision surveying, photo mosaics. Directional minipermeameter measurements are being conducted. Subsurface studies include conventional logs, borehole image log, and core data. Reservoir architectures are reconstructed in four hierarchical levels: multi-storey sandstone, i.e. discrete genetic intervals; individual discrete genetic interval; facies within a discrete genetic interval; and lateral accretion bar deposits. In both outcrop and subsurface, the Bluejacket (Bartlesville) Sandstone comprises two distinctive architectures: a lower braided fluvial and an upper meandering fluvial. Braided fluvial deposits are typically 30 to 80 ft thick, and are laterally persistent filling an incised valley wider than the largest producing fields. The lower contact is irregular with local relief of 50 ft. The braided-fluvial deposits consist of 100-400-ft wide, 5-15-ft thick channel-fill elements. Each channel-fill interval is limited laterally by an erosional contact or overbank deposits, and is separated vertically by discontinuous mudstones or highly concentrated mudstone interclast lag conglomerates. Low-angle parallel-stratified or trough cross-stratified medium- to coarse-grained sandstones volumetrically dominate. This section has a blocky well log profile. Meandering fluvial deposits are typically 100 to 150 ft thick and comprise multiple discrete genetic intervals.

  9. Provenance and weathering depth of carbonaceous gotland sandstone by use of carbon and oxygen isotopes (United States)

    Åberg, G.; Löfvendahl, R.; Stijfhoorn, D.; Råheim, A.

    Carbon and oxygen isotope ratios of carbonates (calcite) from different sites and stratigraphic levels of the Gotland sandstone show that it might be possible to fingerprint the different quarries. Preliminary tests of nine samples of Gotland sandstone from different buildings show that the laser microprobe is an excellent tool for estimating depth of weathering on this carbonaceous sandstone. Analyses perpendicular to the stone surface gave a similar trend for the carbon and oxygen isotope ratios, although changes go deeper with δ13C than δ18O. Depth of weathering is controlled by exposure, location, biologic overgrowth and salt efflorescence. The effect of earlier conservation treatment with linseed oil can also be traced.

  10. Direct hydrocarbon fuel cells (United States)

    Barnett, Scott A.; Lai, Tammy; Liu, Jiang


    The direct electrochemical oxidation of hydrocarbons in solid oxide fuel cells, to generate greater power densities at lower temperatures without carbon deposition. The performance obtained is comparable to that of fuel cells used for hydrogen, and is achieved by using novel anode composites at low operating temperatures. Such solid oxide fuel cells, regardless of fuel source or operation, can be configured advantageously using the structural geometries of this invention.

  11. Shocked cobbles in Lower Cretaceous Duwon Formation, South Korea: their classification and possible formation mechanisms (United States)

    Lim, Hyoun Soo; Chae, Yong-Un; Kim, Kyung Soo; Kim, Cheng-Bin; Huh, Min


    Shocked cobbles are the cobbles having shock-induced deformation structures on the surfaces. The most distinctive macroscopic features are the subparallel fractures and the pervasive surface craters, with or without radial fractures. Until now, these shocked cobbles have been reported mainly in Europe, America, and Africa, but never been found or reported in Korea. Shocked cobbles have recently found in the Lower Cretaceous Duwon Formation in South Korea, which was the second report in Asia. The Duwon Formation consists mainly of conglomerates, gravelly sandstones and intercalated mudstone and shale layers. The shocked cobbles are commonly found in the lowermost clast-supported conglomerate layers, and they show various deformation features, such as pockmarked (circular or elliptical) cobbles, cratered (Hertzian or bowl-shaped) cobbles with or without radial fractures, cobbles showing subparallel fractures, and strongly squashed or heavily dissected cobbles. In general, these deformation structures are considered to have resulted from pressure dissolution by overburden, tectonic compression, and seismic or meteorite impacts. However, the exact formation mechanism is not clearly understood, and still in debate. The shocked cobbles found in the Duwon Formation have similar features to those of previously reported shocked cobbles, especially to Triassic Buntsandstein conglomerates in northeastern Spain. Based on the degree of deformation, the Duwon shocked cobbles can be divided into four types, which are (1) faint contact marks, (2) pitted marks without any fractures, (3) pitted marks with radial or sub-parallel fractures affected by pits, and (4) intensive fractures and heavily dissected fragments. The possible mechanisms for the Duwon shocked cobbles are thought to be crushing process by shear stress and pressure solution.

  12. Structural extremes in a cretaceous dinosaur. (United States)

    Sereno, Paul C; Wilson, Jeffrey A; Witmer, Lawrence M; Whitlock, John A; Maga, Abdoulaye; Ide, Oumarou; Rowe, Timothy A


    Fossils of the Early Cretaceous dinosaur, Nigersaurus taqueti, document for the first time the cranial anatomy of a rebbachisaurid sauropod. Its extreme adaptations for herbivory at ground-level challenge current hypotheses regarding feeding function and feeding strategy among diplodocoids, the larger clade of sauropods that includes Nigersaurus. We used high resolution computed tomography, stereolithography, and standard molding and casting techniques to reassemble the extremely fragile skull. Computed tomography also allowed us to render the first endocast for a sauropod preserving portions of the olfactory bulbs, cerebrum and inner ear, the latter permitting us to establish habitual head posture. To elucidate evidence of tooth wear and tooth replacement rate, we used photographic-casting techniques and crown thin sections, respectively. To reconstruct its 9-meter postcranial skeleton, we combined and size-adjusted multiple partial skeletons. Finally, we used maximum parsimony algorithms on character data to obtain the best estimate of phylogenetic relationships among diplodocoid sauropods. Nigersaurus taqueti shows extreme adaptations for a dinosaurian herbivore including a skull of extremely light construction, tooth batteries located at the distal end of the jaws, tooth replacement as fast as one per month, an expanded muzzle that faces directly toward the ground, and hollow presacral vertebral centra with more air sac space than bone by volume. A cranial endocast provides the first reasonably complete view of a sauropod brain including its small olfactory bulbs and cerebrum. Skeletal and dental evidence suggests that Nigersaurus was a ground-level herbivore that gathered and sliced relatively soft vegetation, the culmination of a low-browsing feeding strategy first established among diplodocoids during the Jurassic.

  13. Structural extremes in a cretaceous dinosaur.

    Directory of Open Access Journals (Sweden)

    Paul C Sereno

    Full Text Available Fossils of the Early Cretaceous dinosaur, Nigersaurus taqueti, document for the first time the cranial anatomy of a rebbachisaurid sauropod. Its extreme adaptations for herbivory at ground-level challenge current hypotheses regarding feeding function and feeding strategy among diplodocoids, the larger clade of sauropods that includes Nigersaurus. We used high resolution computed tomography, stereolithography, and standard molding and casting techniques to reassemble the extremely fragile skull. Computed tomography also allowed us to render the first endocast for a sauropod preserving portions of the olfactory bulbs, cerebrum and inner ear, the latter permitting us to establish habitual head posture. To elucidate evidence of tooth wear and tooth replacement rate, we used photographic-casting techniques and crown thin sections, respectively. To reconstruct its 9-meter postcranial skeleton, we combined and size-adjusted multiple partial skeletons. Finally, we used maximum parsimony algorithms on character data to obtain the best estimate of phylogenetic relationships among diplodocoid sauropods. Nigersaurus taqueti shows extreme adaptations for a dinosaurian herbivore including a skull of extremely light construction, tooth batteries located at the distal end of the jaws, tooth replacement as fast as one per month, an expanded muzzle that faces directly toward the ground, and hollow presacral vertebral centra with more air sac space than bone by volume. A cranial endocast provides the first reasonably complete view of a sauropod brain including its small olfactory bulbs and cerebrum. Skeletal and dental evidence suggests that Nigersaurus was a ground-level herbivore that gathered and sliced relatively soft vegetation, the culmination of a low-browsing feeding strategy first established among diplodocoids during the Jurassic.

  14. Lithofacies, biofacies, and ichnoassemblage evolution of a shallow submarine volcaniclastic fan-shelf depositional system (Upper Cretaceous, James Ross Island, Antarctica) (United States)

    Scasso, R. A.; Olivero, E. B.; Buatois, L. A.

    The Upper Cretaceous (Santonian-Campanian/lower Maastrichtian) Santa Marta Formation on James Ross Island, Antarctica, represents volcaniclastic shallow marine fan and shelf sedimentation adjacent to an active volcanic arc. A combined analysis of sedimentologic, paleoecologic, and ichnologic data allows for the recognition in this unit of six lithofacies associations, eight biofacies, and five trace fossils assemblages. Lithofacies are dominated by fine, massive, tuffaceous rocks; graded, turbidite-like tuffaceous sandstones; carbonaceous mudstones; resedimented conglomerates; coquinas; sandstones; silty sandstones; and minor stromatolite beds. Biofacies are defined by different composition and relative abundance of elements of the benthic fauna, mainly bivalves, gastropods, and serpulids, with minor elements represented by scaphopods, corals, brachiopods, and echinoids. Trace fossil assemblages include the most common elements of the Skolithos and Cruziana ichnofacies. A striking result of the analysis is that lithofacies, biofacies, and trace fossil assemblages form distinct, non-repetitive, vertically successive horizons, with their distribution boundaries roughly coincident. On this basis, seven major facies groups, showing a distinct combination of lithofacies, biofacies, and trace fossils, are distinguished in the Santa Marta Formation. These non-repetitive, vertically stacked facies groups reveal a one-way evolution of the depositional system during a transgressive-regressive cycle, with a new transgression at the top of the unit. The lower facies groups represent shallow marine settings with a very high rate of volcaniclastic sedimentation within subsiding basin. Shallow, volcaniclastic fan systems were probably formed at the base of delta slope and grew rapidly as a consequence of high sedimentary supply in equilibrium with basin subsidence. The upper facies groups probably represent sedimentation within the marine part of the envisaged deltaic system on a


    Energy Technology Data Exchange (ETDEWEB)

    Kent M. Ervin, Principal Investigator


    Gas phase negative ion chemistry methods are employed to determine enthalpies of formation of hydrocarbon radicals that are important in combustion processes and to investigate the dynamics of ion-molecule reactions. Using guided ion beam tandem mass spectrometry, we measure collisional threshold energies of endoergic proton transfer and hydrogen atom transfer reactions of hydrocarbon molecules with negative reagent ions. The measured reaction threshold energies for proton transfer yield the relative gas phase acidities. In an alternative methodology, competitive collision-induced dissociation of proton-bound ion-molecule complexes provides accurate gas phase acidities relative to a reference acid. Combined with the electron affinity of the R {center_dot} radical, the gas phase acidity yields the RH bond dissociation energy of the corresponding neutral molecule, or equivalently the enthalpy of formation of the R{center_dot} organic radical, using equation: D(R-H) = {Delta}{sub acid}H(RH) + EA(R) - IE(H). The threshold energy for hydrogen abstraction from a hydrocarbon molecule yields its hydrogen atom affinity relative to the reagent anion, providing the RH bond dissociation energy directly. Electronic structure calculations are used to evaluate the possibility of potential energy barriers or dynamical constrictions along the reaction path, and as input for RRKM and phase space theory calculations. In newer experiments, we have measured the product velocity distributions to obtain additional information on the energetics and dynamics of the reactions.

  16. Chanco formation, a potential Cretaceous reservoir, central Chile

    Energy Technology Data Exchange (ETDEWEB)

    Cecione, G.


    The Chanco embayment lies 300 km SSW of Santiago, Chile. The sequence within this basin above the metamorphic basement is: Chanco Formation (very clean sandstone), Quiriquina Formation (glauconitic sandstone, rich in organic matter), and Navidad Group (a very good caprock). This section thus contains reservoir, source and caprocks, and is therefore very promising for petroleum investigations. The offshore C-1 well yielded salt-water with gas shows, and two wells drilled onshore yielded shows of gas. The C-1 well lies on a gently-dipping EW-striking anticlinal structure, the presence of which makes the area very prospective.

  17. Palynostratigraphy and paleoenvironmental significance of the Cretaceous succession in the Gebel Rissu-1 well, north Western Desert, Egypt (United States)

    El Beialy, Salah; El-Soughier, Maher; Mohsen, Sayed Abdel; El Atfy, Haytham


    Palynological investigation of the Cretaceous Abu Roash, Bahariya, Kharita, Alamein, Alam El Bueib and Betty formations, encountered in the Gebel Rissu-1 well, north Western Desert, Egypt yielded 27 species of pteridophytic spores, 24 of gymnosperm pollen, 25 of angiosperm pollen and 11 of dinoflagellate cysts in addition to some acritarchs, foraminiferal test linings and freshwater algae. This enabled us to recognize five miospore biozones arranged from youngest to oldest as: Classopollis brasiliensis- Afropollis cf. kahramanensis- Dichastopollenites ghazalataensis Assemblage Zone (Late Cenomanian); Elaterosporites klaszii- Sofrepites legouxae- Afropollis jardinus Assemblage Zone (Middle/Late Albian-Early Cenomanian); Pennipollis peroreticulatus- Duplexisporites generalis-Tricolpates Assemblage Zone (Early Aptian-Early Albian); Tucanopollis crisopolensis- Afropollis sp. Assemblage Zone (Barremian) and Appendicisporites cf. tricornitatus- Ephedripites spp. Assemblage Zone (Late Neocomian). The Early Cretaceous Kharita, Alam El Bueib and the Betty formations encountered in the Gebel Rissu-1 well are interpreted to indicate oxic proximal and distal shelf deposits, characterized by type III/IV, V kerogen, which is gas prone but having little potential to produce hydrocarbons. The Upper Cretaceous Abu Roash and Bahariya formations are characterized by a distal suboxic-anoxic and marginal dysoxic-anoxic environment, and their kerogen type III/II indicates gas/oil prone nature. The Bahariya and Kharita Albian-Cenomanian sediments in the present study witnessed the onset of a semi-arid to arid climate, with local or seasonal humid conditions, based on the continuous high abundance of the elaterates pollen and Afropollis-producing plants that inhabited the paleotropical humid coastal plains.

  18. Fluid migration through sandstone fractures in Gale Crater, Mars (United States)

    Yen, Albert; Blake, David; Bristow, Thomas; Chipera, Steve; Downs, Robert; Gellert, Ralf; Grotzinger, John P.; Ming, Doug; Morris, Richard; Morrison, Shaunna; Rampe, Liz; Thompson, Lucy; Treiman, Allan; Vaniman, David; MSL Science Team


    The Curiosity Mars rover encountered numerous occurrences of light-toned fractures in lithified sediments along its traverse in Gale Crater. These alteration zones can be traced for tens of meters across the landscape and are generally less than a meter in width. Two of these features were investigated in detail by the rover instruments, including drilling to acquire samples both within and immediately outside the lighter-toned areas.The chemical composition established by the Alpha Particle X-ray Spectrometer (APXS) on the arm of the rover shows that the alteration zones are significantly enhanced in silica (40% increase) and sulfur (factor of ~5) relative to the surrounding rocks. Concentrations of Fe, Mg, Al, Mn, Ni and Zn are reduced by a factor of two or more. The correlation between Ca and SO3 indicates the presence of Ca-sulfates, but with up to 15% SO3 (and only 6% to 9% CaO) in the APXS data, the presence of Mg and Fe sulfates in the altered fractures is likely.The Chemistry and Mineralogy (CheMin) X-ray diffraction instrument analyzed the drill fines and found mostly plagioclase feldspar, pyroxenes and magnetite in the unaltered sandstones. X-ray amorphous material and minor hematite and Ca-sulfates are also present. Samples from the alteration zones, however, show a factor of two decrease in the pyroxene to feldspar ratio, abundant Ca-sulfates in various hydration states, and a majority fraction of amorphous material rich in silica and mixed-cation sulfates.The direct comparison of samples within and adjacent to the light toned fractures indicates an alteration process involving the dissolution of pyroxenes and removal of metal cations. The mobility of Al and the likely presence of Fe-sulfates suggest alteration in an acidic environment, but additional moderate pH episodes cannot be ruled out. These features post-date the sandstone lithification and are among the youngest fluid events studied thus far in Gale Crater.

  19. Temperature dependent elasticity and damping in dehydrated sandstone (United States)

    Darling, T. W.; Struble, W.


    Work reported previously at this conference, outlining our observation of anomalously large elastic softening and damping in dehydrated Berea sandstone at elevated temperatures, has been analysed to study shear and compressional effects separately. Modeling of the sample using COMSOL software was necessary to identify modes, as the vibration spectrum of the sample is poorly approximated by a uniform isotropic solid. The first torsional mode of our evacuated, dry, core softens at nearly twice the rate of Young's modulus modes (bending and compressional) and is also damped nearly twice as strongly as temperature increases. We consider two possible models for explaining this behavior, based on the assumption that the mechanical properties of the sandstone are dominated by the framework of quartz grains and polycrystalline cementation, neglecting initially the effects of clay and feldspar inclusions. The 20cm x 2.54cm diameter core is dry such that the pressure of water vapor in the experiment chamber is below 1e-6 Torr at 70C, suggesting that surface water beyond a small number of monolayers is negligible. Our models consider (1) enhanced sliding of grain boundaries in the cementation at elevated temperature and reduced internal water content, and (2) strain microcracking of the cementatioin at low water content due to anisotropic expansion in the quartz grains. In model (1) interfaces parallel to polyhedral grain surfaces were placed in the cement bonds and assigned frictional properties. Model (2) has not yet been implemented. The overall elasticity of a 3-D several-grain model network was determined by modeling quasistatic loading and measuring displacements. Initial results with a small number of grains/bonds suggests that only the first model provides softening and damping for all the modes, however the details of the effects of defect motioin at individual interfaces as the source for the frictional properties is still being evaluated. Nonlinear effects are

  20. Mecaster batnensis (Coquand, 1862), a late Cenomanian echinoid from New Mexico, with a compilation of Late Cretaceous echinoid records in the Western Interior of the United States and Canada (United States)

    Hook, Stephen C.; Cobban, William A.


    Echinoids are rare in the Upper Cretaceous of the Western Interior, where fewer than 60 unique occurrences are known to date, most of these represented by only a few tests or isolated spines. A notable exception is the Carthage coal field (Socorro County, New Mexico), where more than 200 specimens of Mecaster batnensis, previously referred to as Hemiaster jacksoni Maury, 1925, have been collected from the basal Bridge Creek Limestone Beds of the Tokay Tongue of the Mancos Shale. Prolific occurrences from the same beds are known from elsewhere in west-central and southwest New Mexico. Recorded originally from the Upper Cretaceous of Algeria, M. batnensis is a small- to medium-sized, irregular echinoid that is confined to the upper Cenomanian Euomphaloceras septemseriatum Zone in New Mexico. Measurements on 169 well-preserved specimens from two localities in New Mexico document a species that is, on average, 21.0 mm long, 19.8 mm wide, and 15.1 mm tall, yielding a width/length ratio of 0.94 and a height/length ratio of 0.72. Graphs plotting width against length and height against length are strongly linear. The Western Interior echinoid record spans the entire Late Cretaceous, although there are no records from rocks of Santonian age. Localities are spread from New Mexico on the south to Alberta on the north. Preservation ranges from coarse internal molds in high-energy sandstones to original tests in low-energy limestones.

  1. Hydrogeologic information on the Glorieta Sandstone and the Ogallala Formation in the Oklahoma Panhandle and adjoining areas as related to underground waste disposal (United States)

    Irwin, James Haskell; Morton, Robert B.


    The Oklahoma Panhandle and adjacent areas in Texas, Kansas, Colorado, and New Mexico have prospered because of the development of supplies of fresh water and of oil and gas. The Ogallala and, in places, Cretaceous rocks produce fresh water for irrigation, public supply, and domestic and stock use through approximately 9,000 irrigation and public supply wells and a large but undetermined number of other wells. Disposal of oil-field brine and other wastes into the Glorieta Sandstone is of concern to many local residents because of the possibility of pollution of the overlying fresh-water aquifers, particularly the Ogallala Formation. Permits for 147 disposal wells into the Glorieta have been issued in this area. This report summarizes the data on geology, hydrology, and water development currently available to the U.S. Geological Survey. Geologic information indicates that, in the report area, the Glorieta Sandstone lies at depths ranging from about 500 to 1,600 feet below the base of the Ogallala Fox, nation. The rocks between those two formations are of relatively impermeable types, but solution and removal of salt has resulted in collapse of the rocks in some places. Collapse and fracturing of the rocks could result in increased vertical permeability. This might result in movement of brine under hydrostatic head from the Glorieta Sandstone into overlying fresh-water aquifers, in places where an upward hydraulic gradient exists or is created by an increase in pressure within the Glorieta. Abandoned or inadequately sealed boreholes also are possible conduits for such fluids. The mixing of water in the fresh-water aquifers with brines injected into the Glorieta is not known to have occurred anywhere in the report area, but the information available is not adequate to show positively whether or not this may have occurred locally. Much additional information on the stratigraphy and hydrology--particularly, data on the potentiometric surface of water in the Glorieta

  2. Deformation of Aztec Sandstone at Valley of Fire of Nevada: failure modes, sequence of deformation, structural products and their interplay with paleo fluids (United States)

    Aydin, A.


    The Valley of Fire State Park, 60 km NE of Las Vegas, is a beacon of knowledge for deformation of Aztec Sandstone, a cross-bedded quartz arenite deposited in the Aztec-Navajo-Nugget erg in early Jurassic. It displays great diversity of physical properties, different localization types and micromechanics. The two deformation episodes, the Sevier folding & thrusting and the Basin & Range extension affected the area. The appearance of compaction bands marks the earliest deformation structure and their distribution, orientation, and dimension are controlled by the depositional architecture and loading. The earliest shear structures in the area are the Muddy Mountain, Summit, and Willow Tank thrusts and numerous small-scale bed-parallel faults. They altogether produced several kilometers of E-SE transport and shortening in the late Cretaceous and display numerous shear bands in its damage zone within the Aztec Sandstone. Shear bands also occur along dune boundaries and cross-bed interfaces. These observations indicate that the early deformation of the sandstone was accommodated by strain localization with various kinematics. The younger generation of faults in the area is of mid-Miocene age, and crops out pervasively. It includes a series of small offset normal faults (less than a few ten meters) which can be identified at steep cliff faces. These faults are highly segmented and are surrounded by a dense population of splay fractures. A large number of these splays were later sheared sequentially resulting in a well-defined network of left- and right-lateral strike-slip faults with slip magnitudes up to a few kilometers in the Park. The formation mechanisms of both the normal and strike-slip faults can be characterized as the sliding along planes of initial weaknesses and the accompanying cataclastic deformation. Some of the initial weak planes are associated with the depositional elements such as interdune boundaries and cross-bed interfaces while others are joint

  3. The late Cretaceous Arman flora of Magadan oblast, Northeastern Russia (United States)

    Herman, A. B.; Golovneva, L. B.; Shczepetov, S. V.; Grabovsky, A. A.


    The Arman flora from the volcanogenic-sedimentary beds of the Arman Formation is systematically studied using materials from the Arman River basin and the Nelkandya-Khasyn interfluve (Magadan oblast, Northeastern Russia). Seventy-three species of fossil plants belonging to 49 genera are described. They consist of liverworts, horsetails, ferns, seed ferns, cycadaleans, bennettitaleans, ginkgoaleans, czekanowskialeans, conifers, gymnosperms of uncertain systematic affinity, and angiosperms. The Arman flora shows a unique combination, with relatively ancient Early Cretaceous ferns and gymnosperms occurring alongside younger Late Cretaceous plants, primarily angiosperms. The similarity of the Arman flora to the Penzhina and Kaivayam floras of northwestern Kamchatka and the Tylpegyrgynai flora of the Pekul'nei Ridge allows the Arman flora to be dated as Turonian and Coniacian (Late Cretaceous), which is corroborated by isotopic (U-Pb and 40Ar/39Ar) age determination for the plant-bearing layers.

  4. Palaeophytochemical Constituents of Cretaceous Ginkgo coriacea Florin Leaves

    Institute of Scientific and Technical Information of China (English)

    You-Xing Zhao; Cheng-Sen Li; Xiao-Dong Luo; Yu-Fei Wang; Jun Zhou


    Chemical investigation of the organic solvent extract of Cretaceous Ginkgo coriacea Florin leaves by liquid chromatography-mass spectroscopy (LC-MS) and gas chromatography-mass spectrometry (GC-MS), analogous to those from extant leaves of Ginkgo biloba L., led to the detection of a group of natural flavonoids and other volatiles. The similarity of the chemical constituents in these two species of Ginkgo suggest that the secondary metabolism of extant G. biloba is close to that of the Cretaceous species. The remaining natural products may be one explanation why the leaves of the Cretaceous G. coriacea have been preserved morphologically in fossilization. The detection of flavonoids suggests that the leaves of G. coriacea experienced a mild post-depositional environment during their fossilization. This appears to be the oldest occurrence of flavonoids in plant fossils.

  5. A Basal Titanosauriform from the Early Cretaceous of Guangxi, China

    Institute of Scientific and Technical Information of China (English)

    MO Jinyou; WANG Wei; HUANG Zhitao; HUANG Xin; XU Xing


    Based on a partial postcranial skeleton collected from the Lower Cretaceous Napai Formation of Guangxi, China, we erect a new sauropod taxon, Fusuisaurus zhaoi gen. et sp. nov. The holotype specimen consists of the left ilium, left pubis, anterior caudals, most of the dorsal ribs and distal end of the left femur. Fusuisaurus zhaoi is diagnosed by a unique combination of character states among the known sauropods. It displays several synapomorphies of Titanosauriformes but lacks many derived features seen in other titanosauriforms, suggesting that the new taxon represents the basalmost known titanosauriform and providing new evidence that Titanosauriformes originated from Asia. A size comparison suggests that Fusuisaurus zhaoi is among the largest Early Cretaceous sauropods,providing an important addition to the Early Cretaceous Chinese sauropod diversity.

  6. Molecular fossils in Cretaceous condensate from western India

    Indian Academy of Sciences (India)

    Sharmila Bhattacharya; Suryendu Dutta; Ratul Dutta


    The present study reports the biomarker distribution of condensate belonging to the early Cretaceous time frame using gas chromatography-mass spectrometry (GC–MS). The early Cretaceous palaeoenvironment was inscribed into these molecular fossils which reflected the source and conditions of deposition of the condensate. The saturate fraction of the condensate is characterized by normal alkanes ranging from -C9 to -C29} (CPI-1.13), cycloalkanes and C14 and C15 sesquiterpanes. The aromatic fraction comprises of naphthalene, phenanthrene, their methylated derivatives and cyclohexylbenzenes. Isohexylalkylnaphthalenes, a product of rearrangement process of terpenoids, is detected in the condensate. Several aromatic sesquiterpenoids and diterpenoids have been recorded. Dihydro-ar-curcumene, cadalene and ionene form the assemblage of sesquiterpenoids which are indicative of higher plant input. Aromatic diterpenoid fraction comprises of simonellite and retene. These compounds are also indicative of higher plants, particularly conifer source which had been a predominant flora during the Cretaceous time.

  7. Evidence of multi-stage faulting by clay mineral analysis: Example in a normal fault zone affecting arkosic sandstones (Annot sandstones) (United States)

    Buatier, Martine D.; Cavailhes, Thibault; Charpentier, Delphine; Lerat, Jérémy; Sizun, Jean Pierre; Labaume, Pierre; Gout, Claude


    Fault affecting silicoclastic sediments are commonly enriched in clay minerals. Clays are sensitive to fluid-rock interactions and deformation mechanisms; in this paper, they are used as proxy for fault activity and behavior. The present study focuses on clay mineral assemblages from the Point Vert normal fault zone located in the Annot sandstones, a Priabonian-Rupelian turbidite succession of the Alpine foredeep in SE France. In this area, the Annot sandstones were buried around 6-8 km below the front of Alpine nappes soon after their deposition and exhumed during the middle-late Miocene. The fault affects arkosic sandstone beds alternating with pelitic layers, and displays throw of about thirty meters. The fault core zone comprises intensely foliated sandstones bounding a corridor of gouge about 20 cm thick. The foliated sandstones display clay concentration along S-C structures characterized by dissolution of K-feldspar and their replacement by mica, associated with quartz pressure solution, intense microfracturation and quartz vein precipitation. The gouge is formed by a clayey matrix containing fragments of foliated sandstones and pelites. However, a detailed petrographical investigation suggests complex polyphase deformation processes. Optical and SEM observations show that the clay minerals fraction of all studied rocks (pelites and sandstones from the damage and core zones of the fault) is dominated by white micas and chlorite. These minerals have two different origins: detrital and newly-formed. Detrital micas are identified by their larger shape and their chemical composition with a lower Fe-Mg content than the newly-formed white micas. In the foliated sandstones, newly-formed white micas are concentrated along S-C structures or replace K-feldspar. Both types of newly formed micas display the same chemical composition confirmed microstructural observations suggesting that they formed in the same conditions. They have the following structural formulas: Na0

  8. Facies analysis and paleoenvironmental reconstruction of Upper Cretaceous sequences in the eastern Para-Tethys Basin, NW Iran

    Energy Technology Data Exchange (ETDEWEB)

    Omidvar, M.; Safari, A.; Vaziri-Moghaddam, H.; Ghalavand, H.


    Upper Cretaceous mixed carbonate-siliciclastic sequences are among the most important targets for hydrocarbon exploration in the Moghan area, located in the eastern Para-Tethys Basin. Despite of their significance, little is known about their facies characteristics and depositional environments. Detailed facies analysis and paleoenvironmental reconstruction of these sequences have been carried out in eight surface sections. Accordingly, four siliciclastic facies, eight carbonate facies and one volcanic facies have been recognized. Detailed facies descriptions and interpretations, together with the results of facies frequency analysis, standard facies models and Upper Cretaceous depositional models of Para-Tethys Basin, have been integrated and a non-rimmed carbonate platform is presented. This platform was affected by siliciclastic influx, in the form of coastal fan delta and submarine fans in the shallow- to deep-marine parts, respectively. This model is interpreted to be shallower in the central and northeastern parts of the Moghan area. Toward the southeast and southwest, this shallow platform turns into deep marine settings along steep slopes without remarkable marginal barriers. (Author)

  9. Rice Lake National Wildlife Refuge : Sandstone Unit : Mille Lacs National Wildlife Refuge : Fiscal year 2002 (United States)

    US Fish and Wildlife Service, Department of the Interior — This annual narrative report for Rice Lake (including the Sandstone Unit) and Mille Lacs National Wildlife Refuges outlines Refuge accomplishments during the 2002...

  10. Investigating the effect of unloading on artificial sandstone behaviour using the Discrete Element Method (United States)

    Huang, Yueqin; Cheng, Yi Pik; Coop, Matthew


    The Discrete Element Method (DEM) was used to simulate the mechanical behaviour of a reservoir sandstone. Triaxial tests were carried out using 3D-DEM to simulate the stress-strain behaviour of a sandstone with comparisons made between the numerical tests and the laboratory tests. The influence of isotropic unloading was investigated, which was found to have impacts on bond breakages and was successfully captured in the 3D shearing processes. It was found that bond breakages correlated strongly with the stress-strain behaviour of the sandstone affecting the peak strength. It was also found that unloading affected the bond breakages, which then changed the mechanical behaviour of sandstone. The tangent stiffnesses of simulated virgin and cored samples under different confining stresses were compared. From the tangent stiffnesses, gross yield envelopes and the yielding surfaces for unloaded samples and virgin samples were plotted and analysed in detail.

  11. Rice Lake National Wildlife Refuge : Mille Lacs National Wildlife Refuge : Sandstone Unit : Fiscal year 2003 (United States)

    US Fish and Wildlife Service, Department of the Interior — This annual narrative report for Rice Lake (including the Sandstone Unit) and Mille Lacs National Wildlife Refuges outlines Refuge accomplishments during the 2003...

  12. Compactional deformation bands in Wingate Sandstone; additional evidence of an impact origin for Upheaval Dome, Utah (United States)

    Okubo, Chris H.; Schultz, Richard A.


    Field and microstructural observations from Upheaval Dome, in Canyonlands National Park, Utah, show that inelastic strain of the Wingate Sandstone is localized along compactional deformation bands. These bands are tabular discontinuities (Jurassic) age for this impact.

  13. Rice Lake National Wildlife Refuge : Mille Lacs National Wildlife Refuge : Sandstone Unit : Fiscal year 2004 (United States)

    US Fish and Wildlife Service, Department of the Interior — This annual narrative report for Rice Lake (including the Sandstone Unit) and Mille Lacs National Wildlife Refuges outlines Refuge accomplishments during the 2004...


    Institute of Scientific and Technical Information of China (English)


    The beam-particle model is presented for analyzing the progressive failure of particulate composites such as sandstone and concrete. In the model, the medium is schematized as an assembly of particles which are linked through a network of brittle-breaking beam elements. The mechanical behaviour of particle elements is governed by the distinct element method and finite element method. The propagation of the cracking process in particulate composites is mimicked by removing the beam element from the mesh as soon as the stress in the beam exceeds the strength assigned to that particular beam. The new model can be utilized at a meso-scale and in different loading conditions. Two physical experiments are performed to verify the numerical results. The crack patterns and load-displacement response obtained with the proposed numerical model are in good agreement with the experimental results. Moreover, the influence of heterogeneity on crack patterns is also discussed and the correlation existing between the fracture evolution and the loads imposed on the specimen is characterized by fractal dimensions.

  15. Mineral changes in cement-sandstone matrices induced by biocementation

    Energy Technology Data Exchange (ETDEWEB)

    Verba, C. [National Energy Technology Lab. (NETL), Albany, OR (United States); Thurber, A. R. [Oregon State Univ., Corvallis, OR (United States). College of Earth, Ocean, and Atmospheric Sciences; Alleau, Y. [Oregon State Univ., Corvallis, OR (United States). College of Earth, Ocean, and Atmospheric Sciences; Koley, D. [Oregon State Univ., Corvallis, OR (United States). College of Science; Colwell, F. [Oregon State Univ., Corvallis, OR (United States). College of Earth, Ocean, and Atmospheric Sciences; Torres, M. E. [Oregon State Univ., Corvallis, OR (United States). College of Earth, Ocean, and Atmospheric Sciences


    Prevention of wellbore CO2 leakage is a critical component of any successful carbon capture, utilization, and storage program. Sporosarcina pasteurii is a bacterium that has demonstrated the potential ability to seal a compromised wellbore through the enzymatic precipitation of CaCO3. In this paper, we investigate the growth of S. pasteurii in a synthetic brine that mimics the Illinois Basin and on Mt. Simon sandstone encased in Class H Portland cement under high pressure and supercritical CO2 (PCO2) conditions. The bacterium grew optimum at 30 °C compared to 40 °C under ambient and high pressure (10 MPa) conditions; and growth was comparable in experiments at high PCO2. Sporosarcina pasteurii actively induced the biomineralization of CaCO3 polymorphs and MgCa(CO3)2 in both ambient and high pressure conditions as observed in electron microscopy. In contrast, abiotic (non-biological) samples exposed to CO2 resulted in the formation of surficial vaterite and calcite. Finally, the ability of S. pasteurii to grow under subsurface conditions may be a promising mechanism to enhance wellbore integrity.

  16. Experimental study on interaction between simulated sandstone and acidic fluid

    Institute of Scientific and Technical Information of China (English)

    Zhang Yongwang; Zeng Jianhu; Yu Bingsong


    In order to investigate the controlling mechanism of temperature, fluid and other factors on water-rock interaction in the diagenetic process, we performed a series of simulated experiments on the interaction between two kinds of fluids with different salinity and a composite mineral system (simulated sandstone), which contains albite, K-feldspar and other minerals. The experimental results showed that acidity was the most important factor that affected the dissolution of minerals in the composite mineral system. The lower the pH value, the more easily the minerals dissolved. At the same pH value, the dissolution abilities of different acids for various mineral components were also different. Compared to hydrochloric acid (inorganic acid), oxalic acid (organic acid) was more able to dissolve aluminosilicate minerals. However, the dissolution ability of oxalic acid for carbonate minerals was lower than that of hydrochloric acid. In the process of fluid-rock interaction,dissolution of feldspar was relatively complicated. Increase of temperature would accelerate the dissolution of feldspar. Under acidic conditions, albite had a higher dissolution rate than K-feldspar. K-feldspar could dissolve and convert into montmorillonite and kaolinite, while albite could dissolve and convert into kaolinite both at 40℃ and 80℃. Presence of organic acid, and decrease of pH value and water salinity were all favorable for the dissolution of feldspar, but weakened the ability to form clay minerals.

  17. Geometry of calcite cemented zones in shallow marine sandstones

    Energy Technology Data Exchange (ETDEWEB)

    Walderhaug, O.; Prestholm, E.; Oexnevad, I.E.I.


    In offshore oil production, tightly cemented calcite zones often form impermeable barriers to fluid flow an so adversely affect reservoir performance. Based on recent breakthroughs in the theory of the formation of calcite cemented zones, the project discussed in this paper was concerned with (1) Performing outcrop studies in order to increase the existing database on the geometry of calcite cemented zones, (2) Extending and refining methods of predicting the geometry of cored calcite cemented zones, and (3) Applying and illustrating the use of these methods by studying calcite cementation in shallow marine reservoir sandstones on the Norwegian shelf. The paper presents results from field work and applies these results and the criteria for recognizing geometrical forms of calcite cementation in cores to the Ula Formation of the Ula Field and the Rannoch Formation of the Gullfax Field. The results from the core and outcrop studies are integrated in a tentative identification key for cored calcite cemented zones. The work is part of PROFIT (Program for Research On Field oriented Improved recovery Technology), a research project conducted by RF - Rogaland Research in 1991-1994. 32 refs., 10 figs., 2 tabs.

  18. Arctic black shale formation during Cretaceous Oceanic Anoxic Event 2

    DEFF Research Database (Denmark)

    Lenniger, Marc; Nøhr-Hansen, Henrik; Hills, Len V.


    The Late Cretaceous Oceanic Anoxic Event 2 (OAE2) represents a major perturbation of the global carbon cycle caused by the widespread deposition of organic-rich black shales. Although the paleoceanographic response and the spatial extent of bottom-water anoxia in low and mid-paleolatitudes are re......The Late Cretaceous Oceanic Anoxic Event 2 (OAE2) represents a major perturbation of the global carbon cycle caused by the widespread deposition of organic-rich black shales. Although the paleoceanographic response and the spatial extent of bottom-water anoxia in low and mid...

  19. Plant macrofossils of the upper Cretaceous Kaitangata coalfield, New Zealand

    Energy Technology Data Exchange (ETDEWEB)

    Pole, M.; Douglas, B. [University of Queensland, Brisbane, Qld. (Australia). Dept. of Botany


    Uppermost Cretaceous sediments from the Cretaceous Kaitangata Coal Mine and the Wangaloa coast (south of Dunedin, New Zealand) were investigated for dispersed plant macrofossils. The gymnosperms include two cycads (Macrozamia sp. and Pterostoma sp.), Ginkgo sp., three further possible ginkgophyte taxa, and ten conifer taxa. The conifers include two new conifer genera and species, Maikuku stephaniae and Ware riderensis, which are placed in the Taxodiaceae s.l. There are also 13 types of angiosperm cuticle. Sample heterogeneity as regards taxa present and their abundance suggests taxonomic heterogeneity in the original vegetation.

  20. Arctic Late Cretaceous and Paleocene Plant Community Succession (United States)

    Herman, Alexei; Spicer, Robert; Daly, Robert; Jolley, David; Ahlberg, Anders; Moiseeva, Maria


    The Arctic abounds with Late Cretaceous and Paleocene plant fossils attesting to a thriving, diverse, but now extinct polar ecosystem that sequestered vast amounts of carbon. Through detailed examination of plant remains and their distributions in time and space with respect to their entombing sedimentary facies, it has been possible to reconstruct changes in Arctic vegetation composition and dynamics through the Late Cretaceous and into the Paleocene. Based on over 10,000 leaf remains, fossil wood and palynomorph assemblages from northeastern Russia and northern Alaska and palynological data from elsewhere in the Arctic we identify a number of successional plant communities (SPCs) representing seral development from early (pioneer), through middle to late SPCs and climax vegetation. We recognise that (1) Equisetites and some ferns (typically Birisia, but after the beginning of the Maastrichtian, Onoclea) were obligatory components of the early SPCs; (2) first rare angiosperms (e.g. the dicot Vitiphyllum multifidum) appeared in the middle SPCs of the Arctic in the Early - Middle Albian; (3) from late Albian times onwards angiosperms became abundant in the middle SPCs of the Arctic, but were still rare in the earlier and later SPCs; (4) monocots appeared in the Maastrichtian early SPCs; (5) all Arctic Cretaceous late SPCs (and climax vegetation) were dominated by conifers; (6) Arctic SPCs were more numerous and diverse under warm climates than cold; (7) during the Albian and late Cretaceous, advanced (Cenophytic, angiosperm-dominated) plant communities coexisted with those of a more relictual (Mesophytic, dominated by ferns and gymnosperms) aspect, and plants composing these communities did not mix; (8) coal-forming environments (mires) remained conifer, fern and bryophyte dominated throughout the late Cretaceous and Paleocene with little penetration of woody angiosperm components and thus are conservative and predominantly Mesophytic in character; (9) bryophytes

  1. Marine reptiles from the Late Cretaceous of northern Patagonia (United States)

    Gasparini, Z.; Casadio, S.; Fernández, M.; Salgado, L.


    During the Campanian-Maastrichtian, Patagonia was flooded by the Atlantic and reduced to an archipelago. Several localities of northern Patagonia have yielded marine reptiles. Analysis of several assemblages suggests that the diversity and abundance of pelagic marine reptiles in northern Patagonia was higher by the end of the Cretaceous than previously thought. Several plesiosaurids, including Aristonectes parvidens and the polycotylid Sulcusuchus, and the first remains of mosasaurinae have been found. The Cretaceous marine reptile record from South America is scanty. Nevertheless, materials described here suggest that Tethyan and Weddelian forms converged in northern Patagonia, as seen with invertebrates.

  2. Methane seepage in a Cretaceous greenhouse world as evidenced by a peculiar carbonate deposit in the Tarfaya Basin, Morocco (United States)

    Smrzka, Daniel; Zwicker, Jennifer; Kolonic, Sadat; Birgel, Daniel; Little, Crispin; Marzouk, Akmal; Hassane Chellai, El; Wagner, Thomas; Peckmann, Jörn


    The Cretaceous was characterized by major episodes of oceanic anoxic conditions and the large scale deposition of marine black shales rich in organic carbon. Several oceanic anoxic events (OAEs) have been documented during the Cretaceous including the Cenomanian to Turonian OAE 2, which is among the best studied examples to date. This study reports on a large limestone body that occurs within a black shale succession exposed in a coastal section of the Tarfaya Basin, Morocco. The black shales were deposited in the aftermath of OAE 2 in a shallow continental sea. To decipher the mode and causes of carbonate growth in black shales, we use a combination of element geochemistry, palaeontology, thin section petrography, stable isotope geochemistry and lipid biomarker patterns. 13C-depleted biphytanic diacids reveal that the carbonate deposit resulted, at least in part, from microbially-mediated anaerobic oxidation of methane in the shallow subseafloor at a hydrocarbon seep. The lowest obtained δ13C carbonate values of -23.5‰ are not low enough to exclude other carbon sources than methane apart from admixed marine carbonate, indicating a potential contribution from in situ remineralization of organic matter contained in the black shales. Nannofossil and trace metal inventories of the black shales and the macrofaunal assemblage of the carbonate body reveal that environmental conditions became less reducing during the deposition of the background shales that enclose the carbonate body, but the palaeoenvironment was overall mostly characterized by high productivity and episodically euxinic bottom waters. This study provides an insight into the evolution of a hydrocarbon seep that was situated within a shallow continental sea in the aftermath of OAE 2, and sheds light on how these environmental factors influenced carbonate formation and the ecology at the seep site.

  3. Petroleum system elements within the Late Cretaceous and Early Paleogene sediments of Nigeria's inland basins: An integrated sequence stratigraphic approach (United States)

    Dim, Chidozie Izuchukwu Princeton; Onuoha, K. Mosto; Okeugo, Chukwudike Gabriel; Ozumba, Bertram Maduka


    Sequence stratigraphic studies have been carried out using subsurface well and 2D seismic data in the Late Cretaceous and Early Paleogene sediments of Anambra and proximal onshore section of Niger Delta Basin in the Southeastern Nigeria. The aim was to establish the stratigraphic framework for better understanding of the reservoir, source and seal rock presence and distribution in the basin. Thirteen stratigraphic bounding surfaces (consisting of six maximum flooding surfaces - MFSs and seven sequence boundaries - SBs) were recognized and calibrated using a newly modified chronostratigraphic chart. Stratigraphic surfaces were matched with corresponding foraminiferal and palynological biozones, aiding correlation across wells in this study. Well log sequence stratigraphic correlation reveals that stratal packages within the basin are segmented into six depositional sequences occurring from Late Cretaceous to Early Paleogene age. Generated gross depositional environment maps at various MFSs show that sediment packages deposited within shelfal to deep marine settings, reflect continuous rise and fall of sea levels within a regressive cycle. Each of these sequences consist of three system tracts (lowstand system tract - LST, transgressive system tract - TST and highstand system tract - HST) that are associated with mainly progradational and retrogradational sediment stacking patterns. Well correlation reveals that the sand and shale units of the LSTs, HSTs and TSTs, that constitute the reservoir and source/seal packages respectively are laterally continuous and thicken basinwards, due to structural influences. Result from interpretation of seismic section reveals the presence of hanging wall, footwall, horst block and collapsed crest structures. These structural features generally aid migration and offer entrapment mechanism for hydrocarbon accumulation. The combination of these reservoirs, sources, seals and trap elements form a good petroleum system that is viable

  4. Mineralogical controls on NMR rock surface relaxivity: A case study of the Fontainebleau Sandstone (United States)

    Livo, Kurt

    Pore size distribution is derived from nuclear magnetic resonance, but is scaled by surface relaxivity. While nuclear magnetic resonance studies generally focus on the difficulty of determining pore size distribution in unconventional shale reservoirs, there is a lack of discussion concerning pure quartz sandstones. Long surface relaxivity causes complications analyzing nuclear magnetic resonance data for pore size distribution determination. Currently, I am unaware of research that addresses the complicated pore size distribution determination in long relaxing, pure sandstone formations, which is essential to accurate downhole petrophysical modeling. The Fontainebleau sandstone is well known for its homogenous mineralogical makeup and wide range of porosity and permeability. The Hibernia sandstone exhibits a similar mineralogy and is characterized by a similar and porosity-permeability range to the Fontainebleau sandstones, but with a significantly higher portion of clay minerals (1-6%). I present systematic petrophysical properties such as porosity, pore size distribution from nuclear magnetic resonance transverse relaxation times, permeability, and volumetric magnetic susceptibility to aide in characterization of the Fontainebleau sandstone. Analysis of collected nuclear magnetic resonance data is then compared to other petrophysical studies from literature such as helium porosity and permeability, magnetic susceptibility, and electrical conductivity. I find that the lack of impurities on the grain surfaces of pure quartz samples imparts a lower surface relaxivity as compared to clay containing sandstones and makes nuclear magnetic resonance analysis more complex. Thus, inverted nuclear magnetic resonance data from cleaner outcrop samples incorrectly models pore size distribution without accounting for wider surface relaxivity variation and is improperly used when characterizing the Fontainebleau sandstone. This is further supported by evidence from less

  5. Hydrocarbon Accumulation and Distribution Characteristics of the Silurian in the Tazhong Uplift of Tarim Basin (United States)

    LÜ, Xiuxiang; BAI, Zhongkai; ZHAO, Fengyun

    Hydrocarbon accumulation of the Silurian in the Tazhong uplift of Tarim basin is characterized by "two sources and three stages". "Two sources" means that the hydrocarbons are derived from two source rocks of the Cambrian and Middle-Upper Ordovician. "Three stages" means that asphalt and movable oil undergoes three hydrocarbon accumulation stages, i.e., Late Caledonian, Late Hercynian, and Yanshanian-Himalayan. The formation of asphalt resulted from the destruction of the hydrocarbons accumulated and migrated in the early stages. The present movable oil, mostly derived from Middle-Upper Ordovician source rock, resulted from the hydrocarbons accumulated in the late stage. There are three types of reservoirs, i.e., anticline structural, stratigraphic lithological, and lava shield reservoirs in the Tazhong uplift. Hydrocarbon accumulation of the Silurian in the Tazhong uplift is controlled by the three factors. (1) The background of uplift structure. Around the ancient uplift, the compounding of many types makes up the composite hydrocarbon accumulation areas. (2) Effective cover. The show of oil gas including asphalt, heavy crude oil, and normal oil is quite active in the Silurian. Asphalt and heavy crude oil are distributed under the red mudstone member and movable oil is distributed under the gray mudstone member. (3) High quality reservoir bed. Sandstone is distributed widely in the Tazhong area. Reservoir pore space can be divided into three types: a) secondary origin-primary origin pore space; b) primary origin-secondary origin pore space, and c) micropore space. Porosity is 3.3-17.4%, and permeability is (0.1-667.97) × 10 -3 μm 2.

  6. Geologic controls on transgressive-regressive cycles in the upper Pictured Cliffs sandstone and coal geometry in the lower Fruitland Formation, Northern San Juan Basin, New Mexico and Colorado

    Energy Technology Data Exchange (ETDEWEB)

    Ambrose, W.A.; Ayers, W.B. [University of Texas, Austin, TX (United States)


    Three upper Pictured Cliffs Sandstone tongues in the northern part of the San Juan Basin record high-frequency transgressive episodes during the Late Cretaceous and are inferred to have been caused by eustatic sea level rise coincident with differential subsidence. Outcrop and subsurface studies show that each tongue is an amalgamated barrier strand-plain unit up to 100 ft (30 m) thick. Upper Pictured Cliffs barrier strand-plain sandstones underlie and bound thickest Fruitland coal seams on the seaward side. Controls on Fruitland coal-seam thickness and continuity are a function of local facies distribution in a coastal-plain setting, shoreline positions related to transgressive-regressive cycles, and basin subsidence. During periods of relative sea level rise, the Pictured Cliffs shoreline was temporarily stabilized, allowing thick, coastal-plain peats to accumulate. Although some coal seams in the lower Fruitland tongue override abandoned Pictured Cliffs shoreline deposits, many pinch out against them. Differences in the degree of continuity of these coal seams relative to coeval shoreline sandstones are attributed to either differential subsidence in the northern part of the basin, multiple episodes of sea level rise, local variations in accommodation and progradation, stabilization of the shoreline by aggrading peat deposits, or a combination of these factors. Fruitland coalbed methane resources and productivity are partly controlled by coal-seam thickness; other important factors include thermal maturity, fracturing, and overpressuring. The dominant production trend occurs in the northern part of the basin and is oriented northwestward, coinciding with the greatest Fruitland net coal thickness.

  7. Preliminary results in larger benthic foraminifera assemblage in a mixed siliciclastic-carbonate platform from the Upper Cretaceous of the External Prebetic Domain (Valencia province, SE Spain) (United States)

    Robles-Salcedo, Raquel; Vicedo, Vicent


    In the External Prebetic Domain (Betic Mountain Range, Valencia province, SE Spain) it is difficult to find good outcrops to study larger benthic foraminifera (LBF), particularly in the Upper Cretaceous deposits, because of three main reasons. During the Upper Cretaceous, the complex paleogeography in the northern Prebetic Domain developed a complex system of shallow-water platforms. This is directly linked to the complexity in the distribution of the facies observed nowadays, which may change drastically in lateral, closely related outcrops having a special negative impact in the lateral extension of stratigraphical levels containing LBF. The second reason is the nature of the shallow water environments in which the larger foraminifera lived. The local continental influence derived in the establishment of very complex mixed platforms. Thus, there is not a complete register through carbonate rocks, but an alternation of microconglomerates, sandstones, calcarenites and carbonates that can be observed in the stratigraphic series of the Upper Cretaceous. This affects negatively in observing changes in the evolutionary trends of taxa. The third reason difficulting the study of LBF in northern localities of the Prebetic Domain is diagenetic. Dolomitization affects a huge part of the Mesozoic rocks deleting all fossil microfauna in the affected rocks. Such three reasons are behind the difficulty in developing correlations and having a comprehensive understanding of the biostratigraphy and phylogeny of the taxa involved. However, after several field trips developed in the northern Prebetic area, an excellent reference section for the study of the LBF in the Prebetic Domain has been identified in the surroundings of the Pinet village (Valencia province). Here, a relatively continuous section with scarce dolomitization and good conditions of accessibility exists. The larger foraminifera assemblages appering in the Pinet section will be compared with other paleobiogeographic

  8. Effects of Thermal Treatment on the Dynamic Mechanical Properties of Coal Measures Sandstone (United States)

    Li, Ming; Mao, Xianbiao; Cao, Lili; Pu, Hai; Mao, Rongrong; Lu, Aihong


    Many projects such as the underground gasification of coal seams and coal-bed methane mining (exploitation) widely involve the dynamic problems of coal measures sandstone achieved via thermal treatment. This study examines the dynamic mechanical properties of coal measures sandstone after thermal treatment by means of an MTS653 high-temperature furnace and Split Hopkinson pressure bar test system. Experimental results indicate that 500 °C is a transition point for the dynamic mechanical parameters of coal measures sandstone. The dynamic elastic modulus and peak strength increase linearly from 25 to 500 °C while the dynamic peak strain decreases linearly over the same temperature range. The dynamic elastic modulus and peak strength drop quickly from 500 to 800 °C, with a significant increase in the dynamic peak strain over the same temperature range. The rock mechanics are closely linked to material composition and mesoscopic structure. Analysis by X-ray diffraction and scanning electron microscopy indicate that the molecules inside the sandstone increase in density due to the thermal expansion of the material particles, which effectively improves the deformation resistance and carrying capacity of the sandstone and reduces the likelihood of axial deformation. With heat treatment that exceeds 500 °C, the dynamic mechanical properties rapidly weaken due to the decomposition of kaolinite; additionally, hot cracking of the mineral particles within the materials arises from coal sandstone internal porosity, and other defects gradually appear.

  9. Study on pore characteristics and microstructure of sandstones with different grain sizes (United States)

    Li, Huigui; Li, Huamin; Gao, Baobin; Wang, Wen; Liu, Chuang


    The grain sizes have a pronounced influence on the pore characteristics and microstructure of sandstone. This work examined the pore structure and characteristics of three kinds of sandstones with different grain sizes using the scanning electron microscopy (SEM) and nuclear magnetic resonance (NMR) methods and analyzed their grain size distributions, pore size distributions, T2-distributions, and porosity variations. The experimental results showed that sandstones with different grain sizes have significant differences in the microstructures grain size distribution, pore size distribution, T2-distribution, and porosity variation. The results show that coarse, medium and fine sandstones have two peaks in T2-distributions, mean grain size of 398.5, 145.1 and 25.1 μm, respectively, mean pore size of 46.3, 25.9, and 8.4 μm, respectively, porosity of 7.52%, 5.88% and 1.55%, respectively, indicating that both coarse and medium sandstones contain big pores, while fine sandstone contains small pores. This study is of significance for understanding of water migration characteristics in aquifers and gas in coal seams after the working face exploitation.

  10. Improvement of attenuation functions of a clayey sandstone for landfill leachate containment by bentonite addition. (United States)

    Ruiz, Ana I; Fernández, Raúl; Sánchez Jiménez, Nicanor; Rodríguez Rastrero, Manuel; Regadío, Mercedes; de Soto, Isabel S; Cuevas, Jaime


    Enhanced sand-clay mixtures have been prepared by using a sandstone arkosic material and have been evaluated for consideration as landfill liners. A lab-scale test was carried out under controlled conditions with different amended natural sandstones whereby leachate was passed through the compacted mixtures. The compacted samples consisted of siliceous sand (quartz-feldspar sand separated from the arkose sandstone) and clay (purified clay from arkose sandstone and two commercial bentonites) materials that were mixed in different proportions. The separation of mineral materials from a common and abundant natural source, for soil protection purposes, is proposed as an economic and environmentally efficient practice. The liner qualities were compared for their mineralogical, physicochemical and major ions transport and adsorption properties. Although all samples fulfilled hydraulic conductivity requirements, the addition of bentonite to arkose sandstone was determined to be an effective strategy to decrease the permeability of the soil and to improve the pollutants retention. The clay materials from arkose sandstone also contributed to pollutant retention by a significant improvement of the cation exchange capacity of the bulk material. However, the mixtures prepared with clay materials from the arkose, exhibited a slight increase of hydraulic conductivity. This effect has to be further evaluated. Copyright © 2011 Elsevier B.V. All rights reserved.

  11. Brittleness index and seismic rock physics model for anisotropic tight-oil sandstone reservoirs

    Institute of Scientific and Technical Information of China (English)

    Huang Xin-Rui; Huang Jian-Ping; Li Zhen-Chun; Yang Qin-Yong; Sun Qi-Xing; Cui Wei


    Brittleness analysis becomes important when looking for sweet spots in tight-oil sandstone reservoirs. Hence, appropriate indices are required as accurate brittleness evaluation criteria. We construct a seismic rock physics model for tight-oil sandstone reservoirs with vertical fractures. Because of the complexities in lithology and pore structure and the anisotropic characteristics of tight-oil sandstone reservoirs, the proposed model is based on the solid components, pore connectivity, pore type, and fractures to better describe the sandstone reservoir microstructure. Using the model, we analyze the brittleness sensitivity of the elastic parameters in an anisotropic medium and establish a new brittleness index. We show the applicability of the proposed brittleness index for tight-oil sandstone reservoirs by considering the brittleness sensitivity, the rock physics response characteristics, and cross-plots. Compared with conventional brittleness indexes, the new brittleness index has high brittleness sensitivity and it is the highest in oil-bearing brittle zones with relatively high porosity. The results also suggest that the new brittleness index is much more sensitive to elastic properties variations, and thus can presumably better predict the brittleness characteristics of sweet spots in tight-oil sandstone reservoirs.

  12. Factors controlling reservoir quality in tertiary sandstones and their significance to geopressured geothermal production

    Energy Technology Data Exchange (ETDEWEB)

    Loucks, R.G.; Richmann, D.L.; Milliken, K.L.


    Variable intensity of diagenesis is the factor primarily responsible for contrasting regional reservoir quality of Tertiary sandstones from the upper and lower Texas coast. Detailed comparison of Frio sandstone from the Chocolate Bayou/Danbury Dome area, Brazoria County, and Vicksburg sandstones from the McAllen Ranch Field area, Hidalgo County, reveals that extent of diagenetic modification is most strongly influenced by (1) detrital mineralogy and (2) regional geothermal gradients. The regional reservoir quality of Frio sandstones from Brazoria County is far better than that characterizing Vicksburg sandstones from Hidalgo County, especially at depths suitable for geopressured geothermal energy production. However, in predicting reservoir quality on a site-specific basis, locally variable factors such as relative proportions for porosity types, pore geometry as related to permeability, and local depositional environment must also be considered. Even in an area of regionally favorable reservoir quality, such local factors can significantly affect reservoir quality and, hence, the geothermal production potential of a specific sandstone unit.

  13. Tectonic significance of Upper Cretaceous alluvial-fan deposits in the Peninsular Ranges forearc basin complex, Baja California (Mexico)

    Energy Technology Data Exchange (ETDEWEB)

    Fulford, M.; Busby-Spera, C. (Univ. of California, Santa Barbara (USA))


    Recent evidence suggests that forearc basins, previously depicted as broad downwarps, may experience syndepositional faulting and/or folding. The upper Campanian El Gallo Formation, which was deposited along the northern margin of the Rosario embayment of the peninsula Ranges forearc basin complex, records tilting of the underlying arc massif basement contemporaneous with dissection of the arc source terrane. The La Escarpa member at the base of the El Gallo Formation consists of a 100-180-m thick upward-fining sequence, interpreted as a retrogradational proximal to distal alluvial-fan deposit. Overlying the La Escarpa member is the 1,000-m thick El Disecado member, which lies at the top of the El Gallo Formation and consists of sandy fluvial deposits. Conglomerate clast counts from the La Escarpa member and point-count data from sandstones throughout the El Gallo Formation show an upsection increase in granitic and metasedimentary rock fragments relative to volcanic/metavolcanic rock fragments, reflecting unroofing and progressive headward erosion of the source terranes in the Peninsular Ranges. Paleocurrent data from the La Escarpa and El Disecado members suggest a rotation of approximately 110{degree} with time, from west-northwesterly to southerly, reflecting tilting of the basin floor. This may have been accomplished by downdropping along an east-west-trending fault that divided the Rosario embayment into separate subbasins during the Cretaceous.

  14. Shocked cobbles in Lower Cretaceous Duwon Formation, South Korea: A first report in Asia and their possible mechanisms (United States)

    Chae, Y. U.; Kim, K. S.; Kim, C. B.; Son, M.; Lim, H. S.


    Shocked cobbles are the cobbles having shock-induced deformation structures on the surfaces. The most distinctive macroscopic features are the subparallel fractures and the pervasive surface craters, with or without radial fractures. Until now, these shocked cobbles have been reported mainly in Europe (Spain and UK) and N. America (USA and Canada), but never been found or reported in Asia.